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Office of Scientific and Technical Information
Spallation Neutron Source, SNS
NLE Websites -- All DOE Office Websites (Extended Search)
Spallation Neutron Source Spallation Neutron Source Providing the most intense pulsed neutron beams in the world... Accumulator Ring Commissioning Latest Step for Spallation Neutron Source The Spallation Neutron Source, located at Oak Ridge National Laboratory, has passed another milestone on the way to completion this year--the commissioning of the proton accumulator ring. Brookhaven led the design and construction of the accumulator ring, which will allow an order of magnitude more beam power than any other facility in the world. The Spallation Neutron Source (SNS) is an accelerator-based neutron source being built in Oak Ridge, Tennessee, by the U.S. Department of Energy. The figure on the right shows a schematic of the accumulator ring and transport beam lines that are being designed and built by Brookhaven
SNS | Spallation Neutron Source | ORNL
SNS SNS Instruments Working with SNS Contact Us User Program Manager Laura Morris Edwards 865.574.2966 Spallation Neutron Source Home | User Facilities | SNS SNS | Spallation Neutron Source SHARE SNS is an accelerator-based neutron source in Oak Ridge, Tennessee, USA. This one-of-a-kind facility provides the most intense pulsed neutron beams in the world for scientific research and industrial development. The 80-acre SNS site is located on Chestnut Ridge and is part of Oak Ridge National Laboratory. Although most people don't know it, neutron scattering research has a lot to do with our everyday lives. For example, things like medicine, food, electronics, and cars and airplanes have all been improved by neutron scattering research. Neutron research also helps scientists improve materials used in a
SNS Control Group, Spallation Neutron Source, SNS
Control Group at Brookhaven Global Controls References SNS PowerSupply Control - John Smith SNS Diagnostics Control - Peter Cameron SNS Vacuum Control - Johnny Tang SNS Database...
SNS Meetings, Spallation Neutron Source, SNS
SNS Meetings Meetings at BNL - Pam Manning Upcoming Project Office Reviews and Meetings - Bill McGahern BNL SNS Control Group Lunch Meeting - Jenny Weng Top of Page Last Modified:...
SNS Ring, Spallation Neutron Source, SNS
RING RING Lattice Version 1.0 in MAD structure Version 1.1: SNSRing.v.1.1 | 623_620_00.mad Version 1.2 SNSRing.v.1.2 | 623_620_00.mad Matching example MAD optics outputs UAL compatible input example Schematic (one super-period) and mechanical drawing Diagnostics Impedance budget Magnets List and mechanical parameters Mechanical drawings Magnetic field modeling and measurements Installation and survey Power supplies summary and changes Polarity conventions tech.memo and schematic (A polarity) Magnet assemblies Documentation ASAC review presentations DOE review presentations SNS/BNL tech.notes, conference and journal papers SNS/ORNL papers SNS project documentation Other links SNS ring aperture, collimation and beam losses SNS transfer lines SNS/BNL Accelerator Physics SNS/ORNL Accelerator Physics
Documents, Spallation Neutron Source, SNS
Mechanical Released Drawings - Jim Alduino Accelerator System Division Weekly Report BNL SNS Monthly Progress Report - Pam Manning BNL SNS Equipment Status - Pam Manning Design...
SNS/BNL Diagnostics System Group, Spallation Neutron Source, SNS
SNS/BNL Diagnostics System Group SNS/BNL Diagnostics System Group Homepage The Spallation Neutron Source project is a collaboration between six national laboratories of the United states to build a Mega Watt neutrons source driven by a proton accelerator. The complex is going to be build in Oak Ridge (Tennessee) and consists of a full energy (1 Gev) linac, an accumulator ring and a mercury target with several instruments for neutron scattering. Information on the project can be found at http://www.sns.gov. At Brookhaven National Laboratory we work mainly on the accumulator ring and transfer lines diagnostics (HEBT, Ring, RTBT). Some of the systems are SNS-wide ie: the Beam Loss Monitor system and Beam Current Monitor system. In addition our group provides parts of other systems to our partner laboratories. Our group is part or the Collider Accelerator Division that is also in charge of RHIC and the AGS complex. If you are looking for information on a particular topic you can contact the persons working on it.
Spallation Neutron Source The Spallation Neutron Source (SNS)
F/gim F/gim Spallation Neutron Source The Spallation Neutron Source (SNS) gives researchers more detailed informa- tion on the structure and dynamics of physical and biological materials than ever before possible. This accelerator- based facility provides the most intense pulsed neutron beams in the world. Scien- tists are able to count scattered neutrons, measure their energies and the angles at which they scatter, and map their final positions. SNS enables measurements of greater sensitivity, higher speed, higher resolution, and in more complex sample environments than have been possible at existing neutron facilities. Future Growth SNS was designed from the outset to accommodate a second target station, effectively doubling the capacity of the
Opportunities for Neutrino Physics at the Spallation Neutron Source (SNS)
E-Print Network (OSTI)
In this paper we discuss opportunities for a neutrino program at the Spallation Neutrons Source (SNS) being commissioning at ORNL. Possible investigations can include study of neutrino-nuclear cross sections in the energy rage important for supernova dynamics and neutrino nucleosynthesis, search for neutrino-nucleus coherent scattering, and various tests of the standard model of electro-weak interactions.
Yu Efremenko; W R Hix
Review and Workshops, Spallation Neutron Source, SNS
Review and Workshops DOE Review May 7 - 9 2002 SNS Diagnostics Review Agenda July 2002 ICFA Advanced Workshop on HALO Dynamics, Diagnostics, Collimation (HALO '03) Top of Page Last...
Shielding Design of the Spallation Neutron Source (SNS)
Science Conference Proceedings (OSTI)
The shielding design is important for the construction of an intense high-energy accelerator facility like the proposed Spallation Neutron Source (SNS) due to its impact on conventional facility design, maintenance operations, and since the cost for the radiation shielding shares a considerable part of the total facility costs. A calculational strategy utilizing coupled high energy Monte Carlo calculations and multi-dimensional discrete ordinates calculations, along with semi-empirical calculations, was implemented to perform the conceptual design shielding assessment of the proposed SNS. Biological shields have been designed and assessed for the proton beam transport system and associated beam dumps, the target station, and the target service cell and general remote maintenance cell. Shielding requirements have been assessed with respect to weight, space, and dose-rate constraints for operating, shutdown, and accident conditions. A discussion of the proposed facility design, conceptual design shielding requirements, calculational strategy, source terms, preliminary results and conclusions, and recommendations for additional analyses are presented.
Johnson, J.O.
The Spallation Neutron Source (SNS) conceptual design shielding analysis
SciTech Connect
The shielding design is important for the construction of an intense high-energy accelerator facility like the proposed Spallation Neutron Source (SNS) due to its impact on conventional facility design, maintenance operations, and since the cost for the radiation shielding shares a considerable part of the total facility costs. A calculational strategy utilizing coupled high energy Monte Carlo calculations and multi-dimensional discrete ordinates calculations, along with semi-empirical calculations, was implemented to perform the conceptual design shielding assessment of the proposed SNS. Biological shields have been designed and assessed for the proton beam transport system and associated beam dumps, the target station, and the target service cell and general remote maintenance cell. Shielding requirements have been assessed with respect to weight, space, and dose-rate constraints for operating, shutdown, and accident conditions. A discussion of the proposed facility design, conceptual design shielding requirements calculational strategy, source terms, preliminary results and conclusions, and recommendations for additional analyses are presented.
Johnson, J.O.; Odano, N.; Lillie, R.A.
Neutron Imaging @ SNS (NI@SNS 2008)
Neutron Imaging at SNS Workshop (NI@SNS 2008) November 3, 2008 * Building 8600, Central Laboratory & Office Building * Oak Ridge, TN 37831 NI@SNS2008 home Neutron Imaging Agenda...
Neutronic Design Calculations on Moderators for the Spallation Neutron Source (SNS)
DOE Green Energy (OSTI)
The Spallation Neutron Source (SNS) to be built at the Oak Ridge National Laboratory will provide an intense source of neutrons for a large variety of experiments. It consists of a high-energy (1-GeV) and high-power ({approximately}1-MW) proton accelerator, an accumulator ring, together with a target station and an experimental area. In the target itself, the proton beam will produce neutrons via the spallation process and these will be converted to low-energy (<2-eV) neutrons in moderators located close to the target. Current plans are to have two liquid-hydrogen (20-K) moderators and two room-temperature H{sub 2}O moderators. Extensive engineering design work has been conducted on the moderator vessels. For our studies we have produced realistic neutronic representations of these moderators. We report on neutronic studies conducted on these representations of the moderators using Monte Carlo simulation techniques.
Murphy, D.B.
Computational Benchmark Calculations Relevant to the Neutronic Design of the Spallation Neutron Source (SNS)
The Spallation Neutron Source (SNS) will provide an intense source of low-energy neutrons for experimental use. The low-energy neutrons are produced by the interaction of a high-energy (1.0 GeV) proton beam on a mercury (Hg) target and slowed down in liquid hydrogen or light water moderators. Computer codes and computational techniques are being benchmarked against relevant experimental data to validate and verify the tools being used to predict the performance of the SNS. The LAHET Code System (LCS), which includes LAHET, HTAPE ad HMCNP (a modified version of MCNP version 3b), have been applied to the analysis of experiments that were conducted in the Alternating Gradient Synchrotron (AGS) facility at Brookhaven National Laboratory (BNL). In the AGS experiments, foils of various materials were placed around a mercury-filled stainless steel cylinder, which was bombarded with protons at 1.6 GeV. Neutrons created in the mercury target, activated the foils. Activities of the relevant isotopes were accurately measured and compared with calculated predictions. Measurements at BNL were provided in part by collaborating scientists from JAERI as part of the AGS Spallation Target Experiment (ASTE) collaboration. To date, calculations have shown good agreement with measurements.
Gallmeier, F.X.; Glasgow, D.C.; Jerde, E.A.; Johnson, J.O.; Yugo, J.J.
Plasma ignition schemes for the SNS radio-frequency driven H- source
on the Spallation Neutron Source (SNS) Project,� EPAC �98,ignition schemes for the SNS radio-frequency driven H -the Spallation Neutron Source (SNS) is a cesiated, radio-
SNS Instrument Systems | ORNL Neutron Sciences
instrument layout. Click for details. Instruments at the Spallation Neutron Source SNS currently has 13 instruments available for users. Each instrument is designed to complement...
SNS Operations Status Update | ORNL Neutron Sciences
Home SNS Operations Status Update SNS Operations Status Update - November 29, 2012 Resumption of SNS Operations and User Program Neutron production resumed on November 29,...
Recent Performance of the SNS H-Source for 1-MW Neutron Production
This paper describes the performance of the SNS ion source and LEBT as they continue to deliver ~50 mA H- beams at a 5.3% duty factor required for neutron production with a ~1MW proton beam since the fall of 2009. The source continues to deliver persistent H- beams for up to 6 weeks without adding Cs after an initial dose of ~4 mg, except when there are excessive plasma impurities. In one case the H- beam decayed due to an air leak, which is shown to be consistent with sputtering of the Cs layer, and which allows to bracket the plasma potential. In another case, the performance of two sources degraded progressively, which appears to be consistent with a progressive deterioration of the Cs covered Mo converter. These two and other recently discovered issues are discussed in detail.
Stockli, Martin P [ORNL; Han, Baoxi [ORNL; Murray Jr, S N [ORNL; Pennisi, Terry R [ORNL; Santana, Manuel [ORNL; Welton, Robert F [ORNL
The Nanoscale Ordered MAterials Diffractometer NOMAD at the Spallation Neutron Source SNS
The Nanoscale Ordered Materials Diffractometer (NOMAD) is neutron time-of-flight diffractometer designed to determine pair dist ribution functions of a wide range of materials ranging from short range ordered liquids to long range ordered crystals. Due to a large neutron flux provided by the Spallation Neutron Source SNS and a large detector coverage neutron count-rates exceed comparable instruments by one to two orders of magnitude. This is achieved while maintaining a relatively high momentum transfer resolution of a $\\delta Q/Q \\sim 0.8\\%$ FWHM (typical), and an achievable $\\delta Q/Q$ of 0.24\\% FWHM (best). The real space resolution is related to the maximum momentum transfer; A maximum momentum transfer of 50\\AA$^{-1}$ can be achieved routinely and the maximum momentum transfer given by the detector configuration and the incident neutron spectrum is 125 \\AA$^{-1}$. High stability of the source and the detector allow small contrast isotope experiments to be performed. A detailed description of the instrument is given and the results of experiments with standard samples are discussed.
Feygenson, Mikhail [ORNL; Carruth, John William [ORNL; Hoffmann, Ron [ORNL; Chipley, Kenneth King [ORNL; Neuefeind, Joerg C [ORNL
Status of the SNS H- ion source and low-energy beam transport system
Status of the SNS H - Ion Source and Low-Energy Beamto the Spallation Neutron Source (SNS)** Front End and theearly operating phases of SNS. The ion source was derived
Keller, R.; Thomae, R.; Stockli, M.; Welton, R.
The Versatile Neutron Imaging Instrument at SNS | ORNL Neutron...
The Versatile Neutron Imaging Instrument at SNS VENUS: Neutron imaging to advance energy efficiency VENUS: Neutron imaging to advance energy efficiency. As its name indicates,...
Spallation Neutron Source | ORNL Neutron Sciences
Spallation Neutron Source SNS site, Spring 2012 The 80-acre SNS site is located on the east end of the ORNL campus and is about a three-minute drive from her sister neutron...
Shielding and Activation Analyses in Support of the Spallation Neutron Source (SNS) ES{ampersand}H Requirements
Shielding and activation analyses play an important part in determining how to meet the Environmental, Safety and Health (ES{ampersand}H) requirements of an intense high-energy accelerator facility like the proposed Spallation Neutron Source (SNS). The shielding and activation analyses described in this paper were performed primarily using the CALOR code system coupled with MCNP for radiation transport, the ORIHET95 isotope generation and depletion code for activation analysis, and the DOORS multi-dimensional discrete ordinates transport code system for shielding analyses. Additionally, a portion of the shielding calculations were performed with the semi-empirical code - CASL. This paper gives an overview of relevant ES{ampersand}H policies and requirements, and provides detailed discussions of the shielding and activation analyses completed in support of those policies and requirements.
Odano, Naoteru; Johnson, Jeffrey O.; Harrington, R. M.; DeVore, Joe R.
FNPB: the Fundamental Neutron Physics Beam Line at SNS | ORNL...
the Fundamental Neutron Physics Beam Line at SNS FNPB user Elise Martin Users conduct experiments on the most basic of physics questions at the SNS Fundamental Neutron Physics Beam...
The SNS RFQ Commissioning
THE SNS RFQ COMMISSIONING * A. Ratti, J. Ayers, L.Spallation Neutron Source (SNS ** ) project a 402.5 MHz RFQR. Keller et al, �Status of the SNS Font End Systems,� Proc.
Plans for a Neutron EDM Experiment at SNS
The electric dipole moment of the neutron, leptons, and atoms provide a unique window to Physics Beyond the Standard Model. We are currently developing a new neutron EDM experiment (the nEDM Experiment). This experiment, which will be run at the 8.9 A Neutron Line at the Fundamental Neutron Physics Beamline (FNPB) at the Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory, will search for the neutron EDM with a sensitivity two orders of magnitude better than the present limit. In this paper, the motivation for the experiment, the experimental method, and the present status of the experiment are discussed.
Takeyasu M. Ito
Spallation Neutron Source
D/gim D/gim Spallation Neutron Source SNS is an accelerator-based neutron source. This one-of-a-kind facility pro- vides the most intense pulsed neutron beams in the world. When ramped up to its full beam power of 1.4 MW, SNS will be eight times more powerful than today's best facility. It will give researchers more detailed snapshots of the smallest samples of physical and biological materials than ever before
Energy.gov (U.S. Department of Energy (DOE)) Indexed Site
PROGRESS OF THE SPALLATION NEUTRON SOURCE PROJECT, IG-0532 PROGRESS OF THE SPALLATION NEUTRON SOURCE PROJECT, IG-0532 When completed, the Spallation Neutron Source (SNS) will be...
Ion Source Development at the SNS
The Spallation Neutron Source (SNS) now routinely operates near 1 MW of beam power on target with a highly-persistent {approx}38 mA peak current in the linac and an availability of {approx}90%. The {approx}1 ms-long, 60 Hz, {approx}50 mA H{sup -} beam pulses are extracted from a Cs-enhanced, multi-cusp, RF-driven, internal-antenna ion source. An electrostatic LEBT (Low Energy Beam Transport) focuses the 65 kV beam into the RFQ accelerator. The ion source and LEBT have normally a combined availability of {approx}99%. Although much progress has been made over the last years to achieve this level of availability further improvements are desirable. Failures of the internal antenna and occasionally impaired electron dump insulators require several source replacements per year. An attempt to overcome the antenna issues with an AlN external antenna source early in 2009 had to be terminated due to availability issues. This report provides a comprehensive review of the design, experimental history, status, and description of recently updated components and future plans for this ion source. The mechanical design for improved electron dump vacuum feedthroughs is also presented, which is compatible with the baseline and both external antenna ion sources.
Welton, R. F.; Han, B. X.; Kenik, E. A.; Murray, S. N.; Pennisi, T. R.; Potter, K. G.; Lang, B. R.; Santana, M.; Stockli, M. P. [Spallation Neutron Source, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37830-647 (United States); Desai, N. J. [Worcester Polytechnic Institute, Worcester, MA, 01609 (United States)
Radiation transport analyses in support of the SNS Target Station Neutron Beam Line Shutters Title I Design
A detailed radiation transport analysis of the Spallation Neutron Source (SNS) shutters is important for the construction of the SNS because of its impact on conventional facility design, normal operation of the facility, and maintenance operations. Thus far the analysis of the SNS shutter travel gaps has been completed. This analysis was performed using coupled Monte Carlo and multi-dimensional discrete ordinates calculations.
Miller, T.M.; Pevey, R.E.; Lillie, R.A.; Johnson, J.O.
The Vibrational Spectrometer at SNS | ORNL Neutron Sciences
Vibrational Spectrometer at SNS VISION VISION is best thought of as the neutron analogue of an infrared-Raman spectrometer. It is optimized to characterize molecular vibrations in...
VULCAN: the Engineering Materials Diffractometer at SNS | ORNL Neutron
Engineering Materials Diffractometer at SNS Engineering Materials Diffractometer at SNS VULCAN with the multiaxial loadframe on the sample stage. VULCAN with the multiaxial loadframe on the sample stage. VULCAN is designed for deformation, phase transformation, residual stress, texture, and microstructure studies. Load frames, furnaces, battery chargers, and other auxiliary equipment for in situ and time-resolved measurements are integrated in the instrument. As a time-of-flight diffractometer at the world's most intense pulsed, accelerator-based neutron source, VULCAN provides rapid volumetric mapping with a sampling volume of 1 mm3 and a measurement time of minutes for common engineering materials. In extreme cases, VULCAN has the ability to study kinetic behaviors in sub-second time frames. Applications
Performance of the H{sup -} Ion Source Supporting 1-MW Beam Operations at SNS
The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory reached 1-MW of beam power in September 2009, and now routinely operates near 1-MW for the production of neutrons. This paper reviews the performance, operational issues, implemented and planned mitigations of the SNS H{sup -} ion source to support such high power-level beams with high availability. Some results from R and D activities are also briefly described.
Han, B. X.; Hardek, T.; Kang, Y.; Murray, S. N. Jr.; Pennisi, T. R.; Piller, C.; Santana, M.; Welton, R. F.; Stockli, M. P. [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)
Performance of the H- Ion Source Supporting 1-MW Beam Operations at SNS
The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory reached 1-MW of beam power in September 2009, and now routinely operates near 1-MW for the production of neutrons. This paper reviews the performance, operational issues, implemented and planned mitigations of the SNS H- ion source to support such high power-level beams with high availability. Some results from R&D activities are also briefly described.
Han, Baoxi [ORNL; Hardek, Thomas W [ORNL; Kang, Yoon W [ORNL; Murray Jr, S N [ORNL; Pennisi, Terry R [ORNL; Piller, Chip [ORNL; Santana, Manuel [ORNL; Welton, Robert F [ORNL; Stockli, Martin P [ORNL
MaNDi: the Macromolecular Neutron Diffractometer at SNS | ORNL...
The Macromolecular Neutron Diffractometer at SNS MaNDi detector Detector array for the MaNDi instrument before installation. Detector cutaway Cutaway view of detector array for the...
SNS Sample Environment | ORNL Neutron Sciences
Home › Instruments › SNS › Sample Environment Home › Instruments › SNS › Sample Environment SNS Sample Environment SNS Sample Environment Operations Group SNS Sample Environment Operations Group from left to right: (left to right): Bekki Mills, Mark Loguillo, Saad Elorfi, Randy Sexton, Leland Robbins, Matt Rucker, Cory Fletcher, Todd Sherline, Hans-Jochen Lauter, Ken Kroll The Sample Environment Group provides equipment and support for studying materials under controlled conditions (temperature, pressure, magnetic field, chemical environment, etc.). When you come to SNS to conduct an experiment, our front-line teams are there to support you. Although we currently offer a wide range of capabilities, we realize that these capabilities must continually grow. Therefore, we also have a busy research
SNS Instrument System Beam Lines | ORNL Neutron Sciences
SNS Instrument Beam Lines SNS Instrument Beam Lines This diagram shows the beam lines designated for currently funded instruments. Clicking on an instrument description will take you to the page for that instrument. Clicking anywhere else on the image will open a full-size, printable PDF file. SNS Instrument Layout Backscattering Spectrometer (BASIS) Disordered Materials Diffractometer (NOMAD) Wide Angular-Range Chopper Spectrometer (ARCS) Fine-Resolution Fermi Chopper Spectrometer (SEQUOIA) Coming Soon - Vibrational Spectrometer (VISION) Neutron Spin Echo (NSE) Hybrid Spectrometer (HYSPEC) Fundamental Neutron Physics Beamline (FNPB) Single Crystal Diffractometer (TOPAZ) Versatile Neutron Imaging Instrument (VENUS) Macromolecular Diffractometer (MaNDi) Powder Diffractometer (POWGEN3) Engineering Diffractometer (VULCAN) Extended Q-Range Small Angle Neutron Diffractometer (EQ-SANS) Cold Neutron Chopper Spectrometer (CNCS) Liquids (horizontal surface) Reflectometer (LR) Magnetic Advanced Grazing InCidence Spectrometer (MAGICS) High Pressure Diffractometer (SNAP) Coming Soon - Elastic Diffuse Scattering Spectrometer (CORELLI)
SNS Operating Status | ORNL Neutron Sciences
SNS Operating Status Current Beam Status 101713 11:43 Beam is back on target at 485 kW. Power increases will occur throughout the day. Status, Schedules & Alerts Energy and...
SNS Run Schedule for FY 2012 | ORNL Neutron Sciences
Home Facilities SNS SNS Operating Status FY 2012 Run Schedule SNS Run Schedule for FY 2012 (Oct. 2011-Sep. 2012) Printable version Excel version SNS Run Schedule...
SNS Operating Status Alerts SNS Operating Status Alerts Receive updates about the SNS beam status via text messages to your cell phone and/or e-mail by signing up here. The instrument hall coordinators will communicate any significant beam status changes including beam start, beam down, planned and unplanned outages, and unanticipated schedule changes such as delays. On the registration, enter your e-mail address to receive e-mail updates or to receive text messages enter the information below that is specific to your cell phone provider: Carrier Email to SMS Gateway Alltel [10-digit phone number]@message.alltel.com Example:email@example.com AT&T (formerly Cingular) [10-digit phone number]@txt.att.net [10-digit phone number]@mms.att.net (MMS) [10-digit phone number]@cingularme.com
IBIS: An inverse geometry Brillouin inelastic neutron spectrometer for the SNS
The high power target station at the Spallation Neutron Source (SNS) currently has about 20 completed neutron scattering instruments. With a broad coverage of the momentum transfer (Q)-energy (E) space, these instruments serve an extensive user community. In an effort to further expand the scientific capabilities of the SNS instrument suites, we propose a low background, inverse geometry Brillouin inelastic spectrometer for the SNS which will expand the Q-E coverage of the current instrument suite and facilitate the study of inelastic and quasi-elastic scatterings at low Q values. The possible location for the proposed instrument is either beamline 8 which views the decoupled water moderator, or beamline 14A, which views a cold, coupled super critical hydrogen moderator. The instrument parameters, optimizations, and performances at these two beamline locations are discussed.
Zhao, Jinkui [ORNL; Wildgruber, Christoph U [ORNL; Robertson, Lee [ORNL; Herwig, Kenneth W [ORNL
Electron-cloud simulation results for the PSR and SNS
Cloud in the PSR and SNS these proceedings. DISCLAIMER ThisRESULTS FOR THE PSR AND SNS. ? M. Pivi and M. A. Furman, �Spal- lation Neutron Source (SNS) at Oak Ridge, and updated
Pivi, M.; Furman, M.A.
3D-Simulation Studies of SNS Ring Doublet Magnets
3D-SIMULATION STUDIES OF SNS RING DOUBLET MAGNETS* J.G. Wang # , SNS/ORNL, Oak Ridge, TN 37831-6471, U.S.A. N.the Spallation Neutron Source (SNS) at ORNL employs in its
Wang, J.G.; Tsoupas N.; Venturini, M.
-- Why Use Neutrons? -- Neutron Sources -- Continuous vs ...
... Pulsed Sources: -- WNR/PSR LANSCE (Los Alamos). http://lansce.lanl.gov -- SNS (Oak Ridge National Lab). http://www.sns.gov. Page 6. ...
The Wide Angular-Range Chopper Spectrometer at SNS | ORNL Neutron Sciences
The Wide Angular-Range Chopper Spectrometer at SNS The Wide Angular-Range Chopper Spectrometer at SNS and Doug Abernathy at ARCS Materials researcher Judy Pang and instrument scientist Doug Abernathy at ARCS. ARCS is optimized to provide a high neutron flux at the sample and a large solid angle of detector coverage. This spectrometer is capable of selecting incident energies over the full energy spectrum of neutrons, making it useful for studies of excitations from a few to several hundred milli-electron volts. An elliptically shaped supermirror guide in the incident flight path boosts the performance at the lower end of this range. The sample and detector vacuum chambers provide a window-free final flight path and incorporate a large gate valve to allow rapid sample changeout. A T0 neutron chopper not only blocks the prompt radiation from the source
LR: the Liquids Reflectometer at SNS | ORNL Neutron Sciences
The Liquids Reflectometer at SNS Liquids Reflectometer The reflectometry beam line at SNS consists of two separate instruments sharing the same primary shutter, one specialized in...
Electron-cloud updated simulation results for the PSR, and recent results for the SNS
cation in the case of the SNS, we have used a low number ofSpallation Neutron Source (SNS) under con- struction at theparameters for the PSR and SNS. Parameter proton beam energy
NSE: the Neutron Spin Echo Spectrometer at SNS | ORNL Neutron Sciences
Spin Echo Spectrometer at SNS Spin Echo Spectrometer at SNS NSE NSE is funded and operated by the Jülich Centre for Neutron Science. The SNS NSE instrument provides ultrahigh resolution spectroscopy with a Fourier time range that covers τ = 1 ps to a nominal 350 ns with a high effective neutron flux, aiming to be the best of its class in both resolution and dynamic range (please refer to the instrument fact sheet for a detailed current status). Researchers use this instrument to investigate soft condensed matter and complex fluids applications in a variety of fields. The planned optional ferromagnetic and intensity-modulated modes will allow for detailed investigation of magnetic samples and phenomena. The design of the NSE spectrometer takes full advantage of recent progress in neutron optics and polarizing supermirror microbenders,1,2 resulting in
Neutronics studies for a long-wavelength target station at SNS.
The Spallation Neutron Source (SNS), under construction at Oak Ridge National Laboratory, will be the premier facility for neutron scattering studies in the United States. From the outset the SNS can achieve additional flexibility and accommodate a broader range of scientific investigation than would be possible with only the High Power Target Station by utilizing two target stations, each operating under a separate set of conditions and optimized for a certain class of instruments. A second target station, termed the Long-Wavelength Target Station (LWTS), would operate at a lower pulse rate (e.g., 10 vs. 60 Hz) and utilize very cold moderators to emphasize low-energy (long wavelength) neutrons. The LWTS concept discussed here obtains the highest low-energy fluxes possible for neutron scattering instruments by using a heavy-water-cooled solid tungsten target with two moderators in slab geometry and one in a front wing position. The primary focus has been on solid methane moderators, with liquid methane and hydrogen also considered. We used MCNPX to conduct a series of optimization and sensitivity studies to help determine the optimal neutronic parameters of the LWTS. We compared different options based on the thermal and epithermal fluxes as determined by fitting the spectral intensity of the moderators with a Maxwellian peak and a modified Westcott function. The primary parameters are the moderator positions and composition and the target size. We report results for spectral intensity, pulse shapes, high-energy neutron emission, heating profiles in the target, and target activation.
Micklich, B. J.; Iverson, E. B.; Carpenter, J. M.
Wavelength-Shifting-Fiber Scintillation Detectors for Thermal Neutron Imaging at SNS
We have developed wavelength-Shifting-fiber Scintillator Detector (SSD) with 0.3 m2 area per module. Each module has 154 x 7 pixels and a 5 mm x 50 mm pixel size. Our goal is to design a large area neutron detector offering higher detection efficiency and higher count-rate capability for Time-Of-Flight (TOF) neutron diffraction in Spallation Neutron Source (SNS). A ZnS/6LiF scintillator combined with a novel fiber encoding scheme was used to record the neutron events. A channel read-out-card (CROC) based digital-signal processing electronics and position-determination algorithm was applied for neutron imaging. Neutron-gamma discrimination was carried out using pulse-shape discrimination (PSD). A sandwich flat-scintillator detector can have detection efficiency close to He-3 tubes (about 10 atm). A single layer flat-scintillator detector has count rate capability of 6,500 cps/cm2, which is acceptable for powder diffractometers at SNS.
Clonts, Lloyd G [ORNL; Cooper, Ronald G [ORNL; Crow, Lowell [ORNL; Diawara, Yacouba [ORNL; Ellis, E Darren [ORNL; Funk, Loren L [ORNL; Hannan, Bruce W [ORNL; Hodges, Jason P [ORNL; Richards, John D [ORNL; Riedel, Richard A [ORNL; Wang, Cai-Lin [ORNL
Mitigation of the electron-cloud effect in the PSR and SNS proton storage rings by tailoring the bunch profile
CLOUD EFFECT IN THE PSR AND SNS PROTON STORAGE RINGS BYSpallation Neutron Source (SNS) at Oak Ridge, and for theparameters for the PSR and SNS. Parameter Symbol,unit PSR
Neutron source
DOE Patents (OSTI)
A neutron source which is particularly useful for neutron radiography consists of a vessel containing a moderating media of relatively low moderating ratio, a flux trap including a moderating media of relatively high moderating ratio at the center of the vessel, a shell of depleted uranium dioxide surrounding the moderating media of relatively high moderating ratio, a plurality of guide tubes each containing a movable source of neutrons surrounding the flux trap, a neutron shield surrounding one part of each guide tube, and at least one collimator extending from the flux trap to the exterior of the neutron source. The shell of depleted uranium dioxide has a window provided with depleted uranium dioxide shutters for each collimator. Reflectors are provided above and below the flux trap and on the guide tubes away from the flux trap.
Cason, J.L. Jr.; Shaw, C.B.
A neutron source is obtained without employing any separate beryllia receptacle, as was formerly required. The new method is safer and faster, and affords a source with both improved yield and symmetry of neutron emission. A Be container is used to hold and react with Pu. This container has a thin isolating layer that does not obstruct the desired Pu--Be reaction and obviates procedures previously employed to disassemble and remove a beryllia receptacle. (AEC)
Richmond, J.L.; Wells, C.E.
SNS-HFIR User Group Meeting - Neutron Sciences
Committee and Local Contacts Important Dates Weather Attractions logos for SNS, HFIR, SHaRe, and CNMS IMPORTANT INFORMATION: Location of Sessions has changed because of the...
POWGEN - The Powder Diffractometer at SNS - ORNL Neutron Sciences
Powder Diffractometer at SNS POWGEN news: Research makes the cover of Inorganic Chemistry POWGEN detector array POWGEN detector array. POWGEN is a general-purpose powder...
HYSPEC: the Hybrid Spectrometer at SNS | ORNL Neutron Sciences
Hybrid Spectrometer at SNS Hybrid Spectrometer Schematic of the HYSPEC instrument Developed by a team from leading U.S. universities and national laboratories and an international...
CNCS: the Cold Neutron Chopper Spectrometer at SNS | ORNL Neutron Sciences
Cold Neutron Chopper Spectrometer at SNS Cold Neutron Chopper Spectrometer at SNS CNCS detector array Interior of the CNCS detector array. CNCS is a high-resolution, direct-geometry, multi-chopper inelastic spectrometer designed to provide flexibility in the choice of energy resolution and to perform best at low incident energies (2 to 50 meV). Although the detector coverage around the sample is 1.7 sr, a later upgrade to 3 sr is possible. Experiments at CNCS typically use energy resolutions between 10 and 500 µeV. A broad variety of scientific problems, ranging from complex and quantum fluids to magnetism and chemical spectroscopy, are being addressed through experiments at CNCS. Applications Schematic of CNCS (larger image). Complex fluids: dilute protein solutions, biological gels, selective
June 200June6 SNS 100000000-BL0005-R00
June 200June6 SNS 100000000-BL0005-R00 Spallation Neutron Source Project Completion Report June 100000000-BL0005-R00 SPALLATION NEUTRON SOURCE PROJECT COMPLETION REPORT OAK RIDGE NATIONAL LABORATORY June Report SNS 100000000-BL0005-R00 SPALLATION NEUTRON SOURCE COMPLETION REPORT June 2006 Submitted by Thomas
Neutron Cross Section Measurements at the Spallation Neutron Source
With the prospect of construction of the Spallation Neutron Source (SNS) at ORNL, and the fantastic high neutron flux, new, up to now impossible, experiments seem to be feasible in the fields of applied nuclear physics and astrophysics. These experiments will supply crucial neutron-induced cross section data for radionuclides, which are badly needed by many applied physics programs. The SNS will be uniquely suited for measuring the cross sections of interest to nuclear criticality safety, accelerator transmutation of nuclear waste (ATW), and heavy element nucleosynthesis for astrophysics. Because the sample sizes required at current facilities are usually too large for practical measurements, scarce information of these cross sections is available. Using the high neutron flux at the SNS will allow these measurements to be made with samples about 40 times smaller than at the next best facility. The large reduction in sample size at the SNS will result in orders of magnitude reduction in background from the radioactive samples and make them much easier to produce; hence, a much wider range of samples will be accessible for measurement at the SNS than at any other facility.
Guber, K.H.
Getting Beam Time at HFIR and SNS | ORNL Neutron Sciences
Apply for Beam Time at HFIR and SNS Apply for Beam Time at HFIR and SNS Apply for Beam Time at HFIR and SNS 2014B Call for Proposals Proposal call 2014B All available beam lines will accept proposals through February 26, 2014 Beam time is granted through our general user program, which is open to all. In addition, we have opportunities for extended collaboration through programs such as internships and postdoctoral programs. The instruments at HFIR and SNS can be used free of charge with the understanding that researchers will publish their results, making them available to the scientific community. Our facilities are also available for proprietary research for a fee. ORNL User Portal The ORNL User Portal gives you access to all the resources you need as a new or returning user, such as the proposal system, data access and
Facilities and Capabilities | Neutron Science | ORNL
Isotope Reactor and the Spallation Neutron Source. The continuous neutron source at HFIR and the pulsed neutron source at SNS complement each other well and, along with their...
SNS backscattering spectrometer, BASIS
We describe the design and current performance of the backscattering silicon spectrometer (BASIS), a time-of-flight backscattering spectrometer built at the spallation neutron source (SNS) of the Oak Ridge National Laboratory (ORNL). BASIS is the first silicon-based backscattering spectrometer installed at a spallation neutron source. In addition to high intensity, it offers a high-energy resolution of about 3.5 {mu}eV and a large and variable energy transfer range. These ensure an excellent overlap with the dynamic ranges accessible at other inelastic spectrometers at the SNS.
Mamontov, Eugene [ORNL; Herwig, Kenneth W [ORNL
A neutron source of the antimony--beryllium type is presented. The source is comprised of a solid mass of beryllium having a cylindrical recess extending therein and a cylinder containing antimony-124 slidably disposed within the cylindrical recess. The antimony cylinder is encased in aluminum. A berylliunn plug is removably inserted in the open end of the cylindrical recess to completely enclose the antimony cylinder in bsryllium. The plug and antimony cylinder are each provided with a stud on their upper ends to facilitate handling remotely.
Reardon, W.A.; Lennox, D.H.; Nobles, R.G.
The status of the spallation neutron source ion source
The ion source for the spallation neutron source (SNS) is a radio-frequency, multicusp source designed to deliver 45 mA of H2 to the SNS accelerator with a pulse length of 1 ms and repetition rate of 60 Hz. A total of three ion sources have been fabricated and commissioned at Lawrence Berkeley National Laboratory and subsequently delivered to the SNS at the Oak Ridge National Laboratory. The ion sources are currently being rotated between operation on the SNS accelerator, where they are involved in ongoing efforts to commission the SNS LINAC, and the hot spare stand (HSS), where high-current tests are in progress. Commissioning work involves operating the source in a low duty-factor mode (pulse width {approx}200 ms and repetition rate {approx}5 Hz) for extended periods of time while the high-current tests involve source operation at full duty-factor of 6 percent (1 ms/60 Hz). This report discusses routine performance of the source employed in the commissioning role as well as the initial results o f high-current tests performed on the HSS.
Welton, R.F.; Stockli, M.P.; Murray, S.N.; Keller, R.
Measurements of the Thermal Neutron Scattering Kernel
world's most powerful neutron source, the $1.4 billion Spallation Neutron Source At 1.4MW, SNS produces. SNS will feature 24 beamlines for physics, chemistry, biology, materials research. www.sns.gov #12 · Coproduction of epithermal, thermal and cold neutrons #12;SNS Instrument Beam Lines 1st experimentproposed 2nd
Danon, Yaron
Other Links, Spallation Neutron Source, SNS
Other Links ORNL Project Information ORNL Control Web Page ORNL Construction Progress - Real Time WebCam BNLORNL Database...
Science Opportunities at ORNL's Neutron Sources
The Neutron Sciences Directorate at Oak Ridge National Laboratory (ORNL) operates two of the world's most advanced neutron scattering research facilities: the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR). Our vision is to provide unprecedented capabilities for understanding structure and properties across the spectrum of biology, chemistry, physics, and engineering, and to stay at the leading edge of neutron science by developing new instruments, tools, and services. This talk will provide an update on the operations of the two research facilities and highlight the significant research that is emerging. For example, scientists from ORNL are at the forefront of research on a new class of iron-based superconductors based on experiments performed at the Triple-Axis Spectrometer at HFIR and ARCS at SNS. The complementary nature of neutron and x-ray techniques will be discussed to spark discussion among attendees.
Anderson, Ian [ORNL, SNS
Neutron Sources
Table 1 Characteristics of neutron radiography at various neutron-energy ranges...Good discrimination between materials, and ready
Optimization of the Ballistic Guide Design for the SNS FNPB 8.9 A Neutron Line
The optimization of the ballistic guide design for the SNS Fundamental Neutron Physics Beamline 8.9 A line is described. With a careful tuning of the shape of the curve for the tapered section and the width of the straight section, this optimization resulted in more than 75% increase in the neutron flux exiting the 33 m long guide over a straight m=3.5 guide with the same length.
Takeyasu M. Ito; Christopher B. Crawford; Geoffrey L. Greene
A review of the Spallation Neutron Source (SNS) linac beam dynamics is presented. It describes transverse and longitudinal beam optics, losses, activation, and comparison between the initial design and the existing accelerator. The SNS linac consists of normal conducting and superconducting parts. The peculiarities in operations with the superconducting part of the SNS linac (SCL), estimations of total losses in SCL, the possible mechanisms of these losses, and the progress in the transverse matching are discussed.
Shishlo, Andrei P [ORNL
Coherent Scattering Investigations at the Spallation Neutron Source: a Snowmass White Paper
The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, Tennessee, provides an intense flux of neutrinos in the few tens-of-MeV range, with a sharply-pulsed timing structure that is beneficial for background rejection. In this white paper, we describe how the SNS source can be used for a measurement of coherent elastic neutrino-nucleus scattering (CENNS), and the physics reach of different phases of such an experimental program (CSI: Coherent Scattering Investigations at the SNS).
D. Akimov; A. Bernstein; P. Barbeau; P. Barton; A. Bolozdynya; B. Cabrera-Palmer; F. Cavanna; V. Cianciolo; J. Collar; R. J. Cooper; D. Dean; Y. Efremenko; A. Etenko; N. Fields; M. Foxe; E. Figueroa-Feliciano; N. Fomin; F. Gallmeier; I. Garishvili; M. Gerling; M. Green; G. Greene; A. Hatzikoutelis; R. Henning; R. Hix; D. Hogan; D. Hornback; I. Jovanovic; T. Hossbach; E. Iverson; S. R. Klein; A. Khromov; J. Link; W. Louis; W. Lu; C. Mauger; P. Marleau; D. Markoff; R. D. Martin; P. Mueller; J. Newby; J. Orrell; C. O'Shaughnessy; S. Pentilla; K. Patton; A. W. Poon; D. Radford; D. Reyna; H. Ray; K. Scholberg; V. Sosnovtsev; R. Tayloe; K. Vetter; C. Virtue; J. Wilkerson; J. Yoo; C. H. Yu
... for Neutron Reaction Rate Measurements, JA Grundl, V. Spiegel, CM Eisenhauer, HT Heaton II, DM Gilliam (NBS), and J. Bigelow (ORNL), Nucl. ...
Control System Availability for the Spallation Neutron Source
The Spallation Neutron Source (SNS) is continuing its ramp up of beam power, while simultaneously increasing production hours and striving for reduced unplanned downtime. For the large, highly-distributed EPICS-based control system of the SNS, this demand for increased availability is combined with the need for ongoing system maintenance, upgrades and improvements. Causes of recent control system related downtime will be reviewed along with experiences in addressing the competing needs of availability and system improvements.
Hartman, Steven M [ORNL
OscSNS: A Precision Neutrino Oscillation Experiment at the SNS
The growing evidence for short-baseline neutrino oscillations and the possible existence of sterile neutrinos necessitates the development of a cost-effective experiment that can resolve these mysteries. The OscSNS \\cite{1} experiment, located at the Spallation Neutron Source (SNS), Oak Ridge Laboratory, is ideal for this purpose.
OscSNS Collaboration
TAX: Backscattering Spectrometer at SNS | ORNL Neutron Sciences
The Triple-Axis Spectrometer at HFIR Triple-Axis Spectrometer (HB-3) Triple-Axis Spectrometer (HB-3). HB-3 is a colossal flux thermal neutron three-axis spectrometer designed for...
Neutron Science Facilities Operating Status | ORNL Neutron Sciences
Neutron Science Facilities Operating Status High Flux Isotope Reactor The reactor is currently operating at 100% power for fuel cycle 449. Spallation Neutron Source SNS is shutdown...
Optimization of the target of an accelerator-driven neutron source through Monte Carlo numerical simulation of neutron and gamma transport by the
intense neutron beams for research on the structure and dynamics of materials in fields such as physics07-G00050D/gim SpallationNeutronSource SNS is an accelerator-based neutron source. This one-of-a-kind facility pro- vides the most intense pulsed neutron beams in the world. When ramped up to its full beam
Taskaev, Sergey Yur'evich
CORELLI: the Elastic Diffuse Scattering Spectrometer at SNS | ORNL Neutron
The Elastic Diffuse Scattering Spectrometer The Elastic Diffuse Scattering Spectrometer CORELLI The CORELLI instrument. CORELLI is a statistical chopper spectrometer with energy discrimination. It's designed and optimized to probe complex disorder in crystalline materials through diffuse scattering of single-crystal samples. The momentum transfer ranges from 0.5 to 12 Å-1, and the energy of incident neutrons ranges from 10 to 200 meV. This instrument combines the high efficiency of white-beam Laue diffraction with energy discrimination by modulating the beam with a statistical chopper. A cross-correlation method is used to reconstruct the elastic signal from the modulated data. Accurate modeling of the short-range order associated with the diffuse scattering requires measurements over large volumes of three-dimensional reciprocal space, with sufficient momentum
TOPAZ: the Single Crystal Diffractometer at SNS | ORNL Neutron Sciences
TOPAZ-Single-Crystal Diffractometer TOPAZ-Single-Crystal Diffractometer TOPAZ instrument scientist Christina Hoffmann and scientific associate Matt Frost at TOPAZ. TOPAZ instrument scientist Christina Hoffmann and scientific associate Matt Frost at TOPAZ. TOPAZ is an elastic scattering instrument that allows for probing of material structures and responses under controlled environmental conditions. It enables neutron measurement of the same single-crystal samples that is possible with x-ray diffraction. Data are collected on samples of 0.1 mm3 or less. Resolution is such that an average unit cell size of [50 × 50 × 50] Å3 for compounds of moderate complexity can be easily accommodated. This includes inorganic large and porous framework and guest-host materials, metal (in-)organic cluster and
Supercool Neutrons (Ultracold Neutrons)
in the USA. Why neutrons? Neutrons possess physical properties that make them valuable investigative tools Spallation Neutron Source (SNS) The world's most intense pulsed accelerator-based neutron source. High Flux Isotope Reactor (HFIR) The highest flux reactor-based neutron source for condensed matter research
Martin, Jeff
H- radio frequency source development at the Spallation Neutron Source
The Spallation Neutron Source (SNS) now routinely operates nearly 1 MW of beam power on target with a highly persistent {approx}38 mA peak current in the linac and an availability of {approx}90%. H{sup -} beam pulses ({approx}1 ms, 60 Hz) are produced by a Cs-enhanced, multicusp ion source closely coupled with an electrostatic low energy beam transport (LEBT), which focuses the 65 kV beam into a radio frequency quadrupole accelerator. The source plasma is generated by RF excitation (2 MHz, {approx}60 kW) of a copper antenna that has been encased with a thickness of {approx}0.7 mm of porcelain enamel and immersed into the plasma chamber. The ion source and LEBT normally have a combined availability of {approx}99%. Recent increases in duty-factor and RF power have made antenna failures a leading cause of downtime. This report first identifies the physical mechanism of antenna failure from a statistical inspection of {approx}75 antennas which ran at the SNS, scanning electron microscopy studies of antenna surface, and cross sectional cuts and analysis of calorimetric heating measurements. Failure mitigation efforts are then described which include modifying the antenna geometry and our acceptance/installation criteria. Progress and status of the development of the SNS external antenna source, a long-term solution to the internal antenna problem, are then discussed. Currently, this source is capable of delivering comparable beam currents to the baseline source to the SNS and, an earlier version, has briefly demonstrated unanalyzed currents up to {approx}100 mA (1 ms, 60 Hz) on the test stand. In particular, this paper discusses plasma ignition (dc and RF plasma guns), antenna reliability, magnet overheating, and insufficient beam persistence.
Welton, Robert F [ORNL; Pennisi, Terry R [ORNL; Roseberry, Ron T [ORNL; Stockli, Martin P [ORNL
Emittance studies of the SNS external-antenna H- ion source
A new Allison-type emittance scanner has been built to characterize the ion sources and low energy beam transport systems at SNS. In this work, the emittance characteristics of the H- beam produced with the external-antenna RF-driven ion source and transported through the 2-lens electrostatic LEBT are studied. The beam emittance dependence on beam intensity, extraction parameters, and the evolution of the emittance and twiss parameters over beam pulse duration are presented.
Han, Baoxi [ORNL; Stockli, Martin P [ORNL; Welton, Robert F [ORNL; Pennisi, Terry R [ORNL; Murray Jr, S N [ORNL; Santana, Manuel [ORNL; Long, Cary D [ORNL
Data Management Practices | ORNL Neutron Sciences
to data generated from neutron scattering experiments at the High Flux Isotope Reactor (HFIR) and the Spallation Neutron Source (SNS). Any changes to these guidelines will be...
What Can You Do With Neutrons?
the globe, including the Spallation Neutron Source (SNS) and High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). Today the number of active neutron users in...
The Spallation Neutron Source (SNS) successfully met the primary construction project completion milestones in April 2006. An important ingredient of this successful commissioning was the development and use of software tools. With the increasing digitalization of beam diagnostics and increasing complexity of Integrated Control Systems of large accelerators, the need for high level software tools is critical for smooth commissioning. At SNS a special Java based infrastructure called XAL was prepared for beam commissioning. XAL provides a hierarchal view of the accelerator, is data base configured, and includes a physics model of the beam. This infrastructure and individual applications development along with a historical time line of the SNS commissioning will be discussed.
Shishlo, Andrei P [ORNL; Galambos, John D [ORNL
The continued development of the Spallation Neutron Source external antenna H{sup -} ion source
The U.S. Spallation Neutron Source (SNS) is an accelerator-based, pulsed neutron-scattering facility, currently in the process of ramping up neutron production. In order to ensure that the SNS will meet its operational commitments as well as provide for future facility upgrades with high reliability, we are developing a rf-driven, H{sup -} ion source based on a water-cooled, ceramic aluminum nitride (AlN) plasma chamber. To date, early versions of this source have delivered up to 42 mA to the SNS front end and unanalyzed beam currents up to {approx}100 mA (60 Hz, 1 ms) to the ion source test stand. This source was operated on the SNS accelerator from February to April 2009 and produced {approx}35 mA (beam current required by the ramp up plan) with availability of {approx}97%. During this run several ion source failures identified reliability issues, which must be addressed before the source re-enters production: plasma ignition, antenna lifetime, magnet cooling, and cooling jacket integrity. This report discusses these issues, details proposed engineering solutions, and notes progress to date.
Welton, R. F.; Carmichael, J.; Fuga, R.; Goulding, R. H.; Han, B.; Kang, Y.; Lee, S. W.; Murray, S. N.; Pennisi, T.; Potter, K. G.; Santana, M.; Stockli, M. P. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37830-6471 (United States); Desai, N. J. [Worcester Polytechnic Institute, Worcester, Massachusetts 01609 (United States)
Neutron sources and applications
Review of Neutron Sources and Applications was held at Oak Brook, Illinois, during September 8--10, 1992. This review involved some 70 national and international experts in different areas of neutron research, sources, and applications. Separate working groups were asked to (1) review the current status of advanced research reactors and spallation sources; and (2) provide an update on scientific, technological, and medical applications, including neutron scattering research in a number of disciplines, isotope production, materials irradiation, and other important uses of neutron sources such as materials analysis and fundamental neutron physics. This report summarizes the findings and conclusions of the different working groups involved in the review, and contains some of the best current expertise on neutron sources and applications.
Price, D.L. [ed.] [Argonne National Lab., IL (United States); Rush, J.J. [ed.] [National Inst. of Standards and Technology, Gaithersburg, MD (United States)
The Oak Ridge Spallation Neutron Source (SNS) accelerator complex routinely delivers 1 MW of beam power to the spallation target. Due to this high beam power, understanding and minimizing the beam loss is an ongoing focus area of the accelerator physics program. In some areas of the accelerator facility the equipment parameters corresponding to the minimum loss are very different from the design parameters. In this presentation we will summarize the SNS beam loss measurements, the methods used to minimize the beam loss, and compare the design vs. the loss-minimized equipment parameters.
Plum, Michael A [ORNL
Awareness, Preference, Utilization, and Messaging Research for the Spallation Neutron Source and High Flux Isotope Reactor
Oak Ridge National Laboratory (ORNL) offers the scientific community unique access to two types of world-class neutron sources at a single site - the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR). The 85-MW HFIR provides one of the highest steady-state neutron fluxes of any research reactor in the world, and the SNS is one of the world's most intense pulsed neutron beams. Management of these two resources is the responsibility of the Neutron Sciences Directorate (NScD). NScD commissioned this survey research to develop baseline information regarding awareness of and perceptions about neutron science. Specific areas of investigative interest include the following: (1) awareness levels among those in the scientific community about the two neutron sources that ORNL offers; (2) the level of understanding members of various scientific communities have regarding benefits that neutron scattering techniques offer; and (3) any perceptions that negatively impact utilization of the facilities. NScD leadership identified users of two light sources in North America - the Advanced Photon Source (APS) at Argonne National Laboratory and the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory - as key publics. Given the type of research in which these scientists engage, they would quite likely benefit from including the neutron techniques available at SNS and HFIR among their scientific investigation tools. The objective of the survey of users of APS, NSLS, SNS, and HFIR was to explore awareness of and perceptions regarding SNS and HFIR among those in selected scientific communities. Perceptions of SNS and FHIR will provide a foundation for strategic communication plan development and for developing key educational messages. The survey was conducted in two phases. The first phase included qualitative methods of (1) key stakeholder meetings; (2) online interviews with user administrators of APS and NSLS; and (3) one-on-one interviews and traditional and online focus groups with scientists. The latter include SNS, HFIR, and APS users as well as scientists at ORNL, some of whom had not yet used HFIR and/or SNS. These approaches informed development of the second phase, a quantitative online survey. The survey consisted of 16 questions and 7 demographic categorizations, 9 open-ended queries, and 153 pre-coded variables and took an average time of 18 minutes to complete. The survey was sent to 589 SNS/HFIR users, 1,819 NSLS users, and 2,587 APS users. A total of 899 individuals provided responses for this study: 240 from NSLS; 136 from SNS/HFIR; and 523 from APS. The overall response rate was 18%.
Bryant, Rebecca [Bryant Research, LLC; Kszos, Lynn A [ORNL
Collaborative development and operation of large physics experiments is fairly common. Less common is the collaborative development or operation of accelerators. A current example of the latter is the Spallation Neutron Source (SNS). The SNS project was conceived as a collaborative effort between six DOE facilities. In the SNS case, the control system was also developed collaboratively. The SNS project has now moved beyond the collaborative development phase and into the phase where Oak Ridge National Lab (ORNL) is integrating contributions from collaborating ''partner labs'' and is beginning accelerator operations. In this paper, the author reflects on the benefits and drawbacks of the collaborative development of an accelerator control system as implemented for the SNS project from the perspective of a partner lab.
The Extended Q-Range Small Angle Neutron Scattering ...
Abstract Scope, The Extended Q-Range Small Angle Neutron Scattering Diffractometer (EQ-SANS) at the Spallation Neutron Source (SNS) is a high intensity�...
Instrument and Source Design Division | ORNL Neutron Sciences
Ron Crone, RRD Director Ron Crone, RRD Director ISDD Director Ron Crone. Instrument and Source Design Division The Instrument and Source Design Division (ISDD) supports the engineering and development of scientific instruments at the High Flux Isotope Reactor and the Spallation Neutron Source. ISDD continuously develops facilities and capabilities associated with neutron science through research and development. Organization Chart A PDF version of the ISDD Organization Chart is available. Key Division Contacts Director Ron Crone Administrative Assistant Wendy Brooks HFIR Instrument Engineering Doug Selby SNS Instrument Engineering David Vandergriff Instrumentation Projects and Development Ken Herwig Project Management/Operations and Analysis Barbara Thibadeau Source Development and Engineering Analysis Phil Ferguson
Recent improvements to the Spallation Neutron Source (SNS) beam loss monitor (BLM) designs have been made with the goal of significantly reducing background noise. This paper outlines this effort and analyzes the results. The significance of this noise reduction is the ability to use the BLM sensors [1], [2], [3] distributed throughout the SNS accelerator as a method to monitor activation of components as well as monitor beam losses.
Pogge, James R [ORNL; Zhukov, Alexander P [ORNL
The Spallation Neutron Source: A powerful tool for materials research
When completed in 2006, the Spallation Neutron Source (SNS) will use an accelerator to produce the most intense beams of pulsed neutrons in the world. This unique facility is being built by a collaboration of six US Department of Energy laboratories and will serve a diverse community of users drawn from academia, industry, and government labs. The project continues on schedule and within budget, with commissioning and installation of all systems going well. Installation of 14 state-of-the-art instruments is under way, and design work is being completed for several others. These new instruments will enable inelastic and elastic-scattering measurements across a broad range of science such as condensed-matter physics, chemistry, engineering materials, biology, and beyond. Neutron Science at SNS will be complemented by research opportunities at several other facilities under way at Oak Ridge National Laboratory.
Mason, Thom [ORNL; Anderson, Ian S [ORNL; Ankner, John Francis [ORNL; Egami, Takeshi [ORNL; Ekkebus, Allen E [ORNL; Herwig, Kenneth W [ORNL; Hodges, Jason P [ORNL; Horak, Charlie M [ORNL; Horton, Linda L [ORNL; Klose, Frank Richard [ORNL; Mesecar, Andrew D. [University of Illinois, Chicago; Myles, Dean A A [ORNL; Ohl, M. [Forschungszentrum Julich, Julich, Germany; Zhao, Jinkui [ORNL
Tips for Writing Good Proposals for HFIR and SNS | ORNL Neutron...
Tips for Writing Good Proposals for HFIR and SNS Contact instrument staff before writing and ask them about opportunities for collaboration. Staff are available to: Contact...
A method is presented for preparing a neutron source from polonium-210 and substances, such as beryllium and boron, characterized by emission of neutrons upon exposure to alpha particles from the polonium. According to the invention, a source is prepared by placing powdered beryllium and a platinum foil electroplated with polonium-2;.0 in a beryllium container. The container is sealed and then heated by induction to a temperature of 450 to 1100 deg C to volatilize the polonium off the foil into the powder. The heating step is terminated upon detection of a maximum in the neutron flux level.
Birden, J.H.
Neutron Characterization for Additive Manufacturing
such as the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR) shown in Fig. 1 to solve challenging problems in additive manu- facturing (AM)....
News & Events | ORNL Neutron Sciences
or your library directly. December Our Views: Bipartisan state, federal support for SNS necessary Oak Ridger, 1220 The success, thus far, of the Spallation Neutron Source...
SNS target reaches end-of-life
On Sunday, April 3, 2011, the Spallation Neutron Source (SNS) target reached an end-of-life condition, so user operations were shut down to change the stainless steel target housing the liquid mercury. This is the third change out of the target vessel; it is an expected event and took about two weeks. We took advantage of this time to do maintenance work that was planned for the longer summer shutdown. This will shorten that shutdown and recover the neutron production time. SNS restarted user operations on April 20.
Ekkebus, Allen E [ORNL
The Spallation Neutron Source (SNS) has been operating at the MW level for about one year. Experience in beam loss control and machine activation at this power level is presented. Also experience with machine protection systems is reviewed, which is critical at this power level. One of the most challenging operational aspects of high power operation has been attaining high availability, which is also discussed
Galambos, John D [ORNL
Facilities | ORNL Neutron Sciences
Isotope Reactor. The pulsed neutron source at SNS and the continuous neutron source at HFIR complement each other well and, along with their state-of-the-art instruments, provide...
Top neutron scientists named to positions at ORNL | ornl.gov
Department of Energy's Spallation Neutron Source (SNS) and High Flux Isotope Reactor (HFIR), has filled two high-level administrative positions with leaders in the neutron...
In-Situ Neutron Diffraction Study of Recrystallization Kinetics in a ...
Symposium, Neutron and X-Ray Studies of Advanced Materials IV ... engineering materials difffractometer from Spallation Neutron Source [SNS] and at HIPPO�...
A method is presented for preparing a more efficient neutron source comprising inserting in a container a quantity of Po-210, inserting B powder coated with either Ag, Pt, or Ni. The container is sealed and then slowly heated to about 450 C to volatilize the Po and effect combination of the coated powder with the Po. The neutron flux emitted by the unit is moritored and the heating step is terminated when the flux reaches a maximum or selected level.
A time-of-flight backscattering spectrometer at the Spallation Neutron Source, BASIS
Mamontov, E.; Herwig, K. W. [Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
Neutron Scattering Analysis of Magnetostructural Phase ...
Experiments to observe the structural and magnetic phase transformations were performed at the Spallation Neutron Source (SNS) at Oak Ridge National�...
MATERIALS FOR SPALLATION NEUTRON SOURCES: IV: Neutronics
The Department of Energy has initiated a pre-conceptual design study for the National Spallation Neutron Source (NSNS) and given preliminary approval for the�...
How the Spallation Neutron Source Works | ORNL Neutron Sciences
How SNS Works SNS conceptual drawing Conceptual layout of the SNS facility. At full power, SNS will deliver 1.4 million watts (1.4 MW) of beam power onto the target. SNS was...
SNS Returns to Action | ornl.gov
Spallation Neutron Source returns to action Spallation Neutron Source returns to action Knoxville New Sentinel - January 09, 2013 The Spallation Neutron Source, after rocky times this fall due to back-to-back target vessel failures and a two-week shutdown during the holidays, is up and running again, and there are plans to keep it in a production mode through the end of May to make up for lost ground. Operations manager Kevin Jones said the SNS resumed operations for research users at about 8 a.m. on Tuesday. "SNS is operating at the planned power level of 850 kW to preserve target lifetime until a second spare target is available," Jones said in an email message. "All user program instruments are taking beam for experiments and we look forward to a productive long run through May 30, 2013," he said. "During
Core Vessel Insert Handling Robot for the Spallation Neutron Source
The Spallation Neutron Source provides the world's most intense pulsed neutron beams for scientific research and industrial development. Its eighteen neutron beam lines will eventually support up to twenty-four simultaneous experiments. Each beam line consists of various optical components which guide the neutrons to a particular instrument. The optical components nearest the neutron moderators are the core vessel inserts. Located approximately 9 m below the high bay floor, these inserts are bolted to the core vessel chamber and are part of the vacuum boundary. They are in a highly radioactive environment and must periodically be replaced. During initial SNS construction, four of the beam lines received Core Vessel Insert plugs rather than functional inserts. Remote replacement of the first Core Vessel Insert plug was recently completed using several pieces of custom-designed tooling, including a highly complicated Core Vessel Insert Robot. The design of this tool are discussed.
Graves, Van B [ORNL; Dayton, Michael J [ORNL
The most recent beam dynamics studies at the Spallation Neutron Source (SNS) linac, including major beam loss reduction efforts in the normal conducting linac and in the superconducting linac (SCL), and the simulation and measurement of longitudinal beam halo and longitudinal acceptance at the entrance of the SCL are discussed. Oscillation of the beam centroid around the linac synchronous phase and the phase adiabatic damping curves in the SNS linac are investigated with linac longitudinal models and measured with all the linac beam phase monitors.
Zhang, Yan [ORNL
Beam loss is a major concern for high power hadron accelerators such as the Spallation Neutron Source (SNS). An unexpected beam loss in the SNS superconducting linac (SCL) was observed during the power ramp up and early operation. Intra-beam-stripping (IBS) loss, in which interactions between H- particles within the accelerated bunch strip the outermost electron, was recently identified as a possible cause of the beam loss. A set of experiments using proton beam acceleration in the SNS linac was conducted, which supports IBS as the primary beam loss mechanism in the SNS SCL.
Aleksandrov, Alexander V [ORNL; Shishlo, Andrei P [ORNL; Plum, Michael A [ORNL; Lebedev, Valerie [FNAL; Laface, Emanuele [ESS; Galambos, John D [ORNL
Control System for the SNS H- Source Test Stand Allison Scanner
SNS is currently in progress of a multi-year plan to ramp ion beam power to the initial design power of 1.4 MW. Key to reaching this goal is understanding and improving the operation of the H- ion source. An Allison scanner was installed on the ion source test stand to support this improvement. This paper will discuss the hardware and the software control system of the installed Allison scanner. The hardware for the system consists of several parts. The heart of the system is the scanner head, complete with associated bias plates, slits, and signal detector. There are two analog controlled high voltage power supplies to bias the plates in the head, and a motor with associated controller to position the head in the beam. A multifunction data acquisition card reads the signals from the signal detector, as well as supplying the analog voltage control for the power supplies. To synchronize data acquisition with the source, the same timing signal that is used to trigger the source itself is used to trigger data acquisition. Finally, there is an industrial PC to control the rest of the hardware. Control software was developed using National Instruments LabVIEW, and consists of two parts, a data acquisition program to control the hardware, and a stand alone application for offline user data analysis.
Long, Cary D [ORNL; Stockli, Martin P [ORNL; Gorlov, Timofey V [ORNL; Han, Baoxi [ORNL; Pennisi, Terry R [ORNL; Murray Jr, S N [ORNL
Initial observations of cavitation-induced erosion of liquid metal spallation target vessels at the Spallation Neutron Source
During operation of the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory the mechanical properties of the AISI 316L target module are altered by high-energy neutron and proton radiation. The interior surfaces of the target vessel are also damaged by cavitation-induced erosion, which results from repetitive rapid heating of the liquid mercury by high-energy proton beam pulses. Until recently no observations of cavitation-induced erosion were possible for conditions prototypical to the SNS. Post irradiation examination (PIE) of the first and second operational SNS targets was performed to gain insight into the radiation-induced changes in mechanical properties of the 316L target material and the extent of cavitation-induced erosion to the target vessel inner surfaces. Observations of cavitation-induced erosion of the first and second operational SNS target modules are presented here, including images of the target vessel interiors and specimens removed from the target beam-entrance regions.
McClintock, David A [ORNL; Riemer, Bernie [ORNL; Ferguson, Phillip D [ORNL; Carroll, Adam J [ORNL; Dayton, Michael J [ORNL
Opportunities for Neutrino Physics at the Spallation Neutron Source: A White Paper
The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, Tennessee, provides an intense flux of neutrinos in the few tens-of-MeV range, with a sharply-pulsed timing structure that is beneficial for background rejection. In this document, the product of a workshop at the SNS in May 2012, we describe this free, high-quality stopped-pion neutrino source and outline various physics that could be done using it. We describe without prioritization some specific experimental configurations that could address these physics topics.
A. Bolozdynya; F. Cavanna; Y. Efremenko; G. T. Garvey; V. Gudkov; A. Hatzikoutelis; W. R. Hix; W. C. Louis; J. M. Link; D. M. Markoff; G. B. Mills; K. Patton; H. Ray; K. Scholberg; R. G. Van de Water; C. Virtue; D. H. White; S. Yen; J. Yoo
SNS/BNL Accelerator Physics Group page
SNS/BNL Accelerator Systems group SNS/BNL Accelerator Systems group CA-Department Bldg 817 Upton, NY 11973, USA The Spallation Neutron Source project is a collaboration between six national laboratories of the United states to build a MegaWatt neutrons source driven by a proton accelerator. The complex is going to be build in Oak Ridge (Tennessee) and consists of a full energy (1GeV) linac, an accumulator ring and a mercury target with several instruments for neutron scattering. All the information in the project can be found here. At Brookhaven national laboratory we work mainly in the accumulator ring and transfer lines. Our group is part or the Collider Accelerator Division also in charge of RHIC and the AGS complex. If you are looking for information in a particular topic you can contact the persons working on
Design, operational experiences and beam results obtained with the SNS H- ion source and LEBT at Berkeley Lab
of the LEBT Layout for SNS,� Paper MOD19,Linac 2000,Beam Transport Section for the SNS Front-End Systems,� Paper2000). 6. R. Keller for the SNS Front-End Systems team, �
The Spallation Neutron Source (SNS) has recognized the need for developing in-house capability to ensure long term sustainability of the superconducting linac (SCL). SNS has made substantial gains in the last 6 years in understanding SCL operation, including system and equipment limiting factors, and resolution of system and equipment issues. Significant effort and focus is required to assure on-going success in the operation, maintenance, and improvement of the SCL and to address the requirements of the upgrade project for the Second Target Station. These interdependent efforts include implementation of demonstrated improvements, fabrication of spare cryomodules, cavity R&D to enhance machine performance, and related SRF facility developments. Cryomodule and vertical cavity testing facilities are being developed to demonstrate process capabilities and to further understand the collective limitations of installed cavities. The status and future plans for SRF facilities at SNS will be presented.
Kim, Sang-Ho [ORNL; Xu, Ting [ORNL; Afanador, Ralph [ORNL; Howell, Matthew P [ORNL; Crofford, Mark T [ORNL; Stewart, Stephen [ORNL
Accumulator Ring Commissioning Latest Step for Spallation Neutron...
Accumulator Ring Commissioning Latest Step for Spallation Neutron Source BNL SNS Homepage The following is from a press release issued by Oak Ridge National Laboratory. OAK RIDGE,...
The Implementation of a Super Mirror Polarizer at the SNS Fundamental Neutron Physics Beamline
A new bender supermirror polarizer is used to polarize the cold neutron beam at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source. We present the design of a compensation magnet that was built around the polarizer to minimize the polarizer fringe fields that could compromise the magnetic field requirements of the NPDGamma experiment for the field uniformity in the spin rotator and the field direction in the liquid hydrogen target located downstream from the polarizer. The entire magnetic field environment of the experiment has been analyzed using a finite-element model. Measurements of the magnetic field gradients and field direction have been carried out and the results are less than the upper limits required in the experiment. According to the results the compensated fields meet the stringent magnetic field requirements of the experiment defined by the systematic errors that have to be well below the statistical uncertainty of 10 8 in our main observable, the gamma asymmetry in neutron capture on hydrogen. We describe the design of the magnetic field, the construction of the compensation magnet, and we compare results of the field measurements with the results from the model.
Balascuta, S. [Arizona State University; Alarcon, R. [Arizona State University; Baessler, S. [University of Virginia and Oak Ridge National Laboratory (ORNL); Greene, Geoffrey [University of Tennessee, Knoxville (UTK); Mietke, A [Technische Universitat Dresden; Crawford, C. [University of Kentucky, Lexington; Milburn, R. [University of Kentucky, Lexington; Penttila, Seppo [Oak Ridge National Laboratory (ORNL); Prince, J. [University of Virginia, Charlottesville; Sch�dler, J. [Jacobs University, Bremen, Germany & University of Virginia, Charlottesville
Plasma-Wall Interactions in the Cesiated SNS H- Ion Source
High-current H- ion beams are needed to drive high-power accelerators as well as to heat future fusion reactors with neutral beams. The most productive H- sources enhance the production of H- ions with caesium. Cs lowers the work functions of the metal walls, which increases the probability of ions to capture a second electron when bouncing back from the metal plasma walls. However, caesium also causes voltage break downs that can be severe and cause significant downtime. SNS has developed a frugal caesium management, which uses a single injection of ~4 mg of caesium to produce ~50 mA of H- beam without decay for up to 6 weeks. This paper presents calculations and experimental data, which suggest the persistence of the caesium enhanced H- beams are due to 1) thermally limiting the Cs emission, and 2) conditioning for high purity hydrogen plasma, which eliminates the sputtering of Cs by non-hydrogen ions, and 3) hydrogen ions being too light to sputter Cs.
Stockli, Martin P [ORNL
H{sup -} radio frequency source development at the Spallation Neutron Source
Welton, R. F.; Gawne, K. R.; Han, B. X.; Murray, S. N.; Pennisi, T. R.; Roseberry, R. T.; Santana, M.; Stockli, M. P. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37830-6471 (United States); Dudnikov, V. G. [Muons, Inc., 552 N. Batavia Avenue, Batavia, Illinois 60510 (United States); Turvey, M. W. [Villanova University, 800E. Lancaster Ave, Villanova, Pennsylvania 19085 (United States)
DOE/EIS0247; Final Environmental Impact Statement Construction and Operation of the Spallation Neutron Source
SNS FEIS SNS FEIS Cover Sheet COVER SHEET RESPONSIBLE AGENCY: U.S. Department of Energy (DOE) TITLE: Final Environmental Impact Statement (FEIS), Construction and Operation of the Spallation Neutron Source (DOE/EIS-0247) LOCATIONS OF ALTERNATIVE SITES: Illinois, New Mexico, New York, and Tennessee. CONTACT: For further information on this document, write or call: Mr. David Wilfert, EIS Document Manager Oak Ridge Operations Office U.S. Department of Energy 200 Administration Road, 146/FEDC Oak Ridge, TN 37831 Telephone: (800) 927-9964 Facsimile: (423) 576-4542 E-mail: email@example.com Mr. Jeff Hoy, SNS Program Manager Office of Basic Energy Research U.S. Department of Energy (ER-10) Germantown, MD 20874 Telephone: (301) 903-4924 Facsimile: (301) 903-9513 E-mail: firstname.lastname@example.com
Industry - ORNL Neutron Sciences
PartTec PartTec ORNL, PartTec Inc. Licensing Agreement ORNL and PartTec sign licensing agreement (Front) ORNL Deputy Director for Science & Technology Thomas Zacharia and PartTec CEO Herschel Workman. (Back) Bruce Hannan (SNS), PartTec production manager Craig Kline, Rick Riedel (SNS), Jason Hodges (SNS) and Ron Cooper (SNS). The SNS guys were on the development team. Representatives from Oak Ridge National Laboratory and PartTec, an Indiana-based firm, formally signed a licensing agreement Thursday, Aug. 12, to market an advanced neutron detector system developed for the Spallation Neutron Source. The Shifting Scintillator Neutron Detector can determine the time and position of captured neutrons, which enables researchers to obtain very accurate time-of-flight measurements.
Research on fusion neutron sources
The use of fusion devices as powerful neutron sources has been discussed for decades. Whereas the successful route to a commercial fusion power reactor demands steady state stable operation combined with the high efficiency required to make electricity production economic, the alternative approach to advancing the use of fusion is free of many of complications connected with the requirements for economic power generation and uses the already achieved knowledge of Fusion physics and developed Fusion technologies. 'Fusion for Neutrons' (F4N), has now been re-visited, inspired by recent progress achieved on comparably compact fusion devices, based on the Spherical Tokamak (ST) concept. Freed from the requirement to produce much more electricity than used to drive it, a fusion neutron source could be efficiently used for many commercial applications, and also to support the goal of producing energy by nuclear power. The possibility to use a small or medium size ST as a powerful or intense steady-state fusion neutron source (FNS) is discussed in this paper in comparison with the use of traditional high aspect ratio tokamaks. An overview of various conceptual designs of compact fusion neutron sources based on the ST concept is given and they are compared with a recently proposed Super Compact Fusion Neutron Source (SCFNS), with major radius as low as 0.5 metres but still able to produce several MW of neutrons in a steady-state regime.
Gryaznevich, M. P. [Tokamak Solutions UK, Culham Science Centre, Abingdon, OXON, OX133DB (United Kingdom)
Neutron Scattering Science User ...
Proposals for beam time at Oak Ridge National Laboratory's High Flux Isotope Reactor (HFIR) and Spallation Neutron Source (SNS) will be accepted via the web-based proposal system...
Calibrated Neutron Sources
... NIST designed a compliant source. ... needed for new purposes and as old sources decay ... The figure shows a reprentative energy spectrum from such ...
This is the first annual report of the Oak Ridge National Laboratory Neutron Sciences Directorate for calendar year 2007. It describes the neutron science
Welcome 6 Neutron Primer 7 ORNL Neutron Sciences 8 HFIR and SNS 9 Year in Review 16 Science Highlights 36. With HFIR and SNS operating, ORNL now has two of the world's best neutron facilities and the opportunity facilities. At HFIR, the year began with the reactor in shutdown mode and work on the new cold source
The Spallation Neutron Source (SNS) linac system is designed to deliver 1 GeV pulsed H- beams up to 1.56 MW. As beam power was increased from 10 kW to 680 kW in less than three years, beam loss in the accelerator systems C particularly in the superconducting linac (SCL), became more critical. In the previous studies, beam loss in the SCL was mainly attributed to longitudinal problems. However, our most recent simulations have focused on the transverse issues. These include multipole components from magnet imperfections and from dipole corrector windings of the SNS linac quadrupoles. The effects of these multipoles coupled with other transverse errors and a new possible cause of beam loss will be discussed.
Zhang, Yan [ORNL; Allen, Christopher K [ORNL; Holmes, Jeffrey A [ORNL; Galambos, John D [ORNL; Wang, Jian-Guang [ORNL
Conference on New Frontiers in Neutron Macromolecular Crystallography
systems being studied by x-ray diffraction. The advent of the Spallation Neutron Source (SNS) with over an order of magnitude increase in neutron flux, in combination with advances...
"Development and Neutronic Validation of pelletized Cold and Very Cold Moderators for Pulsed Neutron Sources" Phase II Final report
Intense beams of cold neutrons are produced at several DOE facilities and are used by researchers to study the microscopic structure of materials. Energetic neutrons are produced by a high energy proton beam impacting a target. The fast neutrons are converted to the desired cold neutrons passing through a cryogenic moderator vessel, presently filled with dense cold hydrogen gas. Moderators made from solid methane have demonstrated superior performance to the hydrogen moderators but cannot be implemented on high power sources such as the SNS due to the difficulty of removing heat from the solid blocks of methane. Cryogenic Applications F, Inc has developed the methane pellet formation and transport technologies needed to produce a hydrogen cooled solid methane pellet moderator, potentially capable of being used in a high power spallation neutron facility. Such a methane pellet moderator could double the brightness of the neutron beam. Prior to this work a methane pellet moderator had not been produced or studied. The Indiana University LENS facility is a small pulsed neutron source used in part to study and develop cold neutron moderators. In this project cold neutrons were produced in a solid methane pellet moderator and analyzed with the LENS facility diagnostics. The results indicated that the neutron beam formed by the pellet moderator was similar to that of a solid methane block moderator.
Foster, Christopher; Baxter, David V
Cold Neutron and Ultracold Neutron Sources
... Moderators � Solid Methane � CH 4 � CD 4 ... In a cold neutron flux with a continuous spectrum, more neutrons could ... Magneto-vibrational Scatt. + ...
Spallation Neutron Source. ORNL said the Spin Echo was installed on Beam Line 15 at the SNS. Eventually, there'll be 25 research instruments of varying types and capabilities,...
Status of Cryogenic System for Spallation Neutron Source's Superconducting Radiofrequency Test Facility at Oak Ridge National Lab
Spallation Neutron Source (SNS) at Oak Ridge National Lab (ORNL) is building an independent cryogenic system for its Superconducting Radiofrequency Test Facility (SRFTF). The scope of the system is to support the SNS cryomodule test and cavity test at 2-K (using vacuum pump) and 4.5K for the maintenance purpose and Power Upgrade Project of SNS, and to provide the part of the cooling power needed to backup the current CHL to keep Linac at 4.5-K during CHL maintenance period in the future. The system is constructed in multiple phases. The first phase is to construct an independent 4K helium refrigeration system with helium Dewar and distribution box as load interface. It is schedule to be commissioned in 2013. Here we report the concept design of the system and the status of the first phase of this project.
Xu, Ting [ORNL; Casagrande, Fabio [ORNL; Ganni, Venkatarao [ORNL; Knudsen, Peter N [ORNL; Strong, William Herb [ORNL
MATERIALS FOR SPALLATION NEUTRON SOURCES: I: Radiation ...
MATERIALS FOR SPALLATION NEUTRON SOURCES: Session I: Radiation Effects, A. Sponsored by: Jt. SMD/MSD Nuclear Materials Committee Program�...
MATERIALS FOR SPALLATION NEUTRON SOURCES: II: Radiation ...
MATERIALS FOR SPALLATION NEUTRON SOURCES: Session II: Radiation Effects, B. Sponsored by: Jt. SMD/MSD Nuclear Materials Committee Program�...
Design and operation of the wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source
The wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source (SNS) is optimized to provide a high neutron flux at the sample position with a large solid angle of detector coverage. The instrument incorporates modern neutron instrumentation, such as an elliptically focused neutron guide, high speed magnetic bearing choppers, and a massive array of {sup 3}He linear position sensitive detectors. Novel features of the spectrometer include the use of a large gate valve between the sample and detector vacuum chambers and the placement of the detectors within the vacuum, both of which provide a window-free final flight path to minimize background scattering while allowing rapid changing of the sample and sample environment equipment. ARCS views the SNS decoupled ambient temperature water moderator, using neutrons with incident energy typically in the range from 15 to 1500 meV. This range, coupled with the large detector coverage, allows a wide variety of studies of excitations in condensed matter, such as lattice dynamics and magnetism, in both powder and single-crystal samples. Comparisons of early results to both analytical and Monte Carlo simulation of the instrument performance demonstrate that the instrument is operating as expected and its neutronic performance is understood. ARCS is currently in the SNS user program and continues to improve its scientific productivity by incorporating new instrumentation to increase the range of science covered and improve its effectiveness in data collection.
Abernathy, D. L.; Stone, M. B.; Loguillo, M. J.; Lucas, M. S.; Delaire, O. [Neutron Scattering Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831 (United States); Tang, X.; Lin, J. Y. Y.; Fultz, B. [California Institute of Technology, W. M. Keck Laboratory 138-78, Pasadena, California 91125 (United States)
The wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source (SNS) is optimized to provide a high neutron flux at the sample position with a large solid angle of detector coverage. The instrument incorporates modern neutron instrumentation, such as an elliptically-focused neutron guide, high speed magnetic bearing choppers and a massive array of 3He linear position sensitive detectors. Novel features of the spectrometer include the use of a large gate valve between the sample and detector vacuum chambers and the placement of the detectors within the vacuum, both of which provide a window-free final flight path to minimize background scattering while allowing rapid changing of the sample and sample environment equipment. ARCS views the SNS decoupled ambient temperature water moderator, using neutrons with incident energy typically in the range from 15 to 1500 meV. This range, coupled with the large detector coverage, allows a wide variety of studies of excitations in condensed matter, such as lattice dynamics and magnetism, in both powder and single-crystal samples. Comparisons of early results to both analytical and Monte Carlo simulation of the instrument performance demonstrate that the instrument is operating as expected and its neutronic performance is understood. ARCS is currently in the SNS user program, and continues to improve its scientific productivity by incorporating new instrumentation to increase the range of science covered and improve its effectiveness in data collection.
Abernathy, Douglas L [ORNL; Stone, Matthew B [ORNL; Loguillo, Mark [ORNL; Lucas, Matthew [Air Force Research Laboratory, Wright-Patterson AFB, OH; Delaire, Olivier A [ORNL; Tang, Xiaoli [California Institute of Technology, Pasadena; Lin, J. Y. Y. [California Institute of Technology, Pasadena; Fultz, B. [California Institute of Technology, Pasadena
Commissioning of the SNS front-end systems at Berkeley Lab
Results Obtained with the SNS H - Ion Source and LEBT atVarious contributions by SNS authors to these conferenceCOMMISSIONING OF THE SNS FRONT-END SYSTEMS AT BERKELEY LAB*
Neutron S ource SNS User Office: 865-574-4600 08-G00333Bgim TO MELTON VALLEY DRIVE HFIR PARKING WALK-IN ENTRY 7900 7964K - HFIR USER OFFICE RM 18 7972 HFIR H igh Flux Isotope...
Overview of SNS accelerator shielding analyses
The Spallation Neutron Source is an accelerator driven neutron scattering facility for materials research. During all phases of SNS development, including design, construction, commissioning and operation, extensive neutronics work was performed in order to provide adequate shielding, to assure safe facility operation from radiation protection point of view, and to optimize performance of the accelerator and target facility. Presently, most of the shielding work is concentrated on the beam lines and instrument enclosures to prepare for commissioning, safe operation and adequate radiation background in the future. Although the accelerator is built and in operation mode, there is extensive demand for shielding and activation analyses. It includes redesigning some parts of the facility, facility upgrades, designing additional structures, storage and transport containers for accelerator structures taken out of service, and performing radiation protection analyses and studies on residual dose rates inside the accelerator. (authors)
Popova, I.; Gallmeier, F. X.; Ferguson, P.; Iverson, E.; Lu, W. [ORNL/SNS, MS6475, PO Box 2008, Oak Ridge, TN 37831-6471 (United States)
Requirements of minimum beam loss for hand-on maintenance and flexibility for future operations are essential for the lattice design of the Spallation Neutron Source (SNS) accumulator ring. In this paper, we present a hybrid lattice that consists of FODO arcs and doublet straights, emphasizing injection and collimation optimization and flexibility, split tunes for coupling control, sextupole families for chromaticity control, and compatibility to future upgrades.
Advanced Neutron Source enrichment study
A study has been performed of the impact on performance of using low enriched uranium (20% {sup 235}U) or medium enriched uranium (35% {sup 235}U) as an alternative fuel for the Advanced Neutron Source, which is currently designed to use uranium enriched to 93% {sup 235}U. Higher fuel densities and larger volume cores were evaluated at the lower enrichments in terms of impact on neutron flux, safety, safeguards, technical feasibility, and cost. The feasibility of fabricating uranium silicide fuel at increasing material density was specifically addressed by a panel of international experts on research reactor fuels. The most viable alternative designs for the reactor at lower enrichments were identified and discussed. Several sensitivity analyses were performed to gain an understanding of the performance of the reactor at parametric values of power, fuel density, core volume, and enrichment that were interpolations between the boundary values imposed on the study or extrapolations from known technology.
Bari, R.A.; Ludewig, H.; Weeks, J.R.
SHUG Chairman's Message | ORNL Neutron Sciences Users
shall be the Spallation Neutron Source (SNS) and High Flux Isotope Reactor (HFIR) User Group, "SHUG." II. PURPOSE The purpose of the SHUG is to: Provide a formal and...
Neutron Scattering Facilities 1982
NEUTRON SOURCES NEUTRON SOURCES Types of Sources U.S. Sources Available for Users Plans for the Future The Neutron Scattering Society of America (NSSA) SNS/ANL School on Neutron and x-Ray Scattering, June 2011 Jim Rhyne Lujan Neutron Scattering Center Los Alamos National Lab. What do we need to do neutron scattering? * Neutron Source - produces neutrons * Diffractometer or Spectrometer - Allows neutrons to interact with sample - Sorts out discrete wavelengths by monochromator (reactor) or by time of flight (pulse source) - Detectors pick up neutrons scattered from sample * Analysis methods to determine material properties * Brain power to interpret results Sources of neutrons for scattering * Nuclear Reactor - Neutrons produced from fission of 235 U - Fission spectrum neutrons
MATERIALS FOR SPALLATION NEUTRON SOURCES: III: Corrosion
Both liquid mercury and liquid lead-bismuth eutectic have been proposed as possible target materials for spallation neutron sources. During the 1950's and�...
Switchable radioactive neutron source device
This invention is a switchable neutron generating apparatus comprised of a pair of plates, the first plate having an alpha emitter section on it and the second plate having a target material portion on it which generates neutrons when its nuclei absorb an alpha particle. In operation, the alpha portion of the first plate is aligned with the neutron portion of the second plate to produce neutrons and brought out of alignment to cease production of neutrons. 3 figs.
Stanford, G.S.; Rhodes, E.A.; Devolpi, A.; Boyar, R.E.
Imaging and Neutrons - IAN 2006 - Neutron Sciences
SNS Home Saturday, January 11, 2014 SNS Home Saturday, January 11, 2014 Go IAN 2006 Imaging and Neutrons 2006 October 23-25, 2006 Iran Thomas Auditorium Central Laboratory and Office Building Spallation Neutron Source Oak Ridge National Laboratory, Oak Ridge, TN Who Should Attend Synopsis Goals and Expected Outcomes Application Areas Techniques International Advisory Committee Local Organizing Committee Agenda with Presentations NEW Confirmed Speakers Frequently Asked Questions - FAQ Satellite Workshop - Progress in Electron Volt Neutron Spectroscopy eV Worshop Agenda presentations NEW Lodging, Transportation, Bus Schedule Location Directions and Map Registration CLOSED Abstracts, Posters, Contributed Talks Scholarships Sponsors Vendors May Attend Relevant Reports Important Dates Weather Attractions
Fourteen High Voltage Converter Modulators (HVCM) were initially installed at the Spallation Neutron Source Linear Accelerator (SNS Linac) at the Oak Ridge National Laboratory in 2005. A fifteenth HVCM was added in 2009. Each modulator provides a pulse of up to 140 kV at a maximum width of 1.35 msec. Peak power level is 11 MW with an 8% duty factor. The HVCM system must be available for neutron production (NP) 24/7 with the exception being two, 6-week maintenance periods per year. HVCM reliability is one of the most important factors to maximize Linac availability and achieve SNS performance goals. During the last few years several modifications have been implemented to improve the overall system reliability. This paper presents operational history of the HVCM systems and examines failure mode statistical data since the modulators began operating at 60 Hz. System enhancements and upgrades aimed at providing long term reliable operation with minimal down time are also discussed in the paper.
Peplov, Vladimir V [ORNL; Anderson, David E [ORNL; Cutler, Roy I [ORNL; Hicks, Jim [ORNL; Saethre, Robert B [ORNL; Wezensky, Mark W [ORNL
International workshop on cold neutron sources
The first meeting devoted to cold neutron sources was held at the Los Alamos National Laboratory on March 5--8, 1990. Cosponsored by Los Alamos and Oak Ridge National Laboratories, the meeting was organized as an International Workshop on Cold Neutron Sources and brought together experts in the field of cold-neutron-source design for reactors and spallation sources. Eighty-four people from seven countries attended. Because the meeting was the first of its kind in over forty years, much time was spent acquainting participants with past and planned activities at reactor and spallation facilities worldwide. As a result, the meeting had more of a conference flavor than one of a workshop. The general topics covered at the workshop included: Criteria for cold source design; neutronic predictions and performance; energy deposition and removal; engineering design, fabrication, and operation; material properties; radiation damage; instrumentation; safety; existing cold sources; and future cold sources.
Russell, G.J.; West, C.D. (comps.) (Los Alamos National Lab., NM (United States)) [comps.; Los Alamos National Lab., NM (United States)
Neutron scattering workshop promotes high-pressure research ...
long-term goals in these areas closer to reality, Oak Ridge National Laboratory (ORNL), home of the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor, is hosting...
Neutron dosimetry at SLAC: Neutron sources and instrumentation
This report summarizes in detail the dosimetric characteristics of the five radioisotopic type neutron sources ({sup 238}PuBe, {sup 252}Cf, {sup 238}PuB, {sup 238}PuF{sub 4}, and {sup 238}PuLi) and the neutron instrumentation (moderated BF{sub 3} detector, Anderson-Braun (AB) detector, AB remmeter, Victoreen 488 Neutron Survey Meter, Beam Shut-Off Ionization Chamber, {sup 12}C plastic scintillator detector, moderated indium foil detector, and moderated and bare TLDs) that are commonly used for neutron dosimetry at the Stanford Linear Accelerator Center (SLAC). 36 refs,. 19 figs.
Liu, J.C.; Jenkins, T.M.; McCall, R.C.; Ipe, N.E.
The Cold Neutron Source core
... walls are necessary for the containment of the ... a recombination of radiolysis products is induced in ... Neutrons are produced by fission with energies ...
Advanced Neutron Source (ANS) Project progress report
This report discusses the following topics on the advanced neutron source: quality assurance (QA) program; reactor core development; fuel element specification; corrosion loop tests and analyses; thermal-hydraulic loop tests; reactor control concepts; critical and subcritical experiments; material data, structural tests, and analysis; cold source development; beam tube, guide, and instrument development; hot source development; neutron transport and shielding; I C research and development; facility concepts; design; and safety.
McBee, M.R.; Chance, C.M. (eds.) (Oak Ridge National Lab., TN (USA)); Selby, D.L.; Harrington, R.M.; Peretz, F.J. (Oak Ridge National Lab., TN (USA))
Fission fragment driven neutron source
Fissionable uranium formed into a foil is bombarded with thermal neutrons in the presence of deuterium-tritium gas. The resulting fission fragments impart energy to accelerate deuterium and tritium particles which in turn provide approximately 14 MeV neutrons by the reactions t(d,n).sup.4 He and d(t,n).sup.4 He.
Miller, Lowell G. (Idaho Falls, ID); Young, Robert C. (Idaho Falls, ID); Brugger, Robert M. (Columbia, MO)
Producing persistent, high-current, high-duty-factor H{sup -} beams for routine 1 MW operation of Spallation Neutron Source (invited)
Since 2009, the Spallation Neutron Source (SNS) has been producing neutrons with ion beam powers near 1 MW, which requires the extraction of {approx}50 mA H{sup -} ions from the ion source with a {approx}5% duty factor. The 50 mA are achieved after an initial dose of {approx}3 mg of Cs and heating the Cs collar to {approx}170 deg. C. The 50 mA normally persist for the entire 4-week source service cycles. Fundamental processes are reviewed to elucidate the persistence of the SNS H{sup -} beams without a steady feed of Cs and why the Cs collar temperature may have to be kept near 170 deg. C.
Stockli, Martin P.; Han, B. X.; Hardek, T. W.; Kang, Y. W.; Murray, S. N.; Pennisi, T. R.; Piller, C.; Santana, M.; Welton, R. [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
Modulating the Neutron Flux from a Mirror Neutron Source
A 14-MeV neutron source based on a Gas-Dynamic Trap will provide a high flux of 14 MeV neutrons for fusion materials and sub-component testing. In addition to its main goal, the source has potential applications in condensed matter physics and biophysics. In this report, the author considers adding one more capability to the GDT-based neutron source, the modulation of the neutron flux with a desired frequency. The modulation may be an enabling tool for the assessment of the role of non-steady-state effects in fusion devices as well as for high-precision, low-signal basic science experiments favoring the use of the synchronous detection technique. A conclusion is drawn that modulation frequency of up to 1 kHz and modulation amplitude of a few percent is achievable. Limitations on the amplitude of modulations at higher frequencies are discussed.
Ryutov, D D
Neutron production by cosmic-ray muons at shallow depth J. Busenitz,1
SNSsiteincludingsupport facilitiesandtheCenter forNanophaseMaterials Sciences. SpallationNeutronSource The Spallation Neutron Source (SNS) is an accelerator-based science fa- cility that will provide neutron beams, magnetic materials, polymers and complex fluids, chemistry, and biology. What is the importance of neutron
Gratta, Giorgio
The accumulator ring of the Spallation Neutron Source (SNS) at ORNL employs in its straight sections closely packed quadrupole doublemagnets with large aperture of R=15.1 cm an relatively short iron-to-iron distance of 51.4 cm. These quads have much extended fringe field, and magnetic interferences among them in the doublet assemblies is not avoidable. Though each magnet in the assemblies has been individually mapped to high accuracy of lower than 0.01 percent level, the experimental data including the magnetic interference effect will not be available. We have performed 3D computing simulations on a quadrupole doublet model in order to assess the degree of the interference and to obtain relevant data for the SNS commissioning and operation.
A beam profile monitor for H-beams based on laser photoneutralization is being developed at Brookhaven National Laboratory (BNL) for use on the Spallation Neutron Source (SNS) [l]. An H ion has a first ionization potential of 0.75eV and can be neutralized by light from a Nd:YAG laser (h=1064nm). To measure beam profiles, a narrow laser beam is passed through the ion beam neutralizing a portion of the H-beam struck by the laser. The laser trajectory is stepped across the ion beam. At each laser position, the reduction of the beam current caused by the laser is measured. A proof-of-principle experiment was done earlier at 750keV. This paper reports on measurements made on 200MeV beam at BNL and with a compact scanner prototype at Lawrence Berkeley National Lab on beam from the SNS RFQ.
Portable Low Energy Neutron Source - Industrial Partnerships Office
Typically, sources of low energy neutrons are large and immobile, often filling entire rooms. A portable source of low energy neutrons would allow for accurate and ...
SNAP: the Spallation Neutrons and Pressure Diffractometer at...
Spallation Neutrons and Pressure Diffractometer at SNS Spallation Neutrons and Pressure Diffractometer. Spallation Neutrons and Pressure Diffractometer. The SNAP Diffractometer...
Data Processing for the SNS EQ-SANS Diffractometer
The scattering data on the Extended Q-Range Small Angle Scattering Diffractometer at the Spallation Neutron Source are stored as neutron events. Each event has two parts: the time of fight of the detected neutron, and an identifier for the neutron's location on the detector. In addition, each event is associated with the source pulse from which the neutron is originated. Due to the high neutron beam intensity at the SNS, the size of the stored data files can easily exceed several Gigabytes. Processing and reducing these data can be very time consuming. The standard way of handling the data at the SNS has been to first transform the data into histograms. On the EQ-SANS, these histograms are further processed into intensity I vs. neutron momentum transfer Q files, I(Q). For a large data, the whole process can take many minutes to hours to complete, which severely limits the turnaround time of an experiment. Experimenters often want to reduce the data quickly and depending on the result, make decisions on the setup of next measurements. They may also need to reduce the data using different inputs and conditions. In this work, we present the implementation of a fast data processing scheme for the EQ-SANS diffractometer. The scattering data are processed directly from neutron event files into I(Q) or other desired formats, greatly reducing the needed computation time. Further speed gains are obtained by the implementation of parallel computing under the Message Passing Interface framework. Most data on the EQ-SANS can now be handled in mere seconds. The process is highly automated. All relevant experimental information that is stored in instrument configuration files are read and processed. In addition, the new implementation is highly flexible. All the data corrections and handlings can be controlled transparently through user inputs. Finally, software implementation enables the slicing of neutron event, which can be used for the study of time dependent phenomena.
Zhao, Jinkui [ORNL
Aspects of a high intensity neutron source
A unique methodology for creating a neutron source model was developed for deuterons and protons incident on solid phase beryllium and lithium targets. This model was then validated against experimental results already ...
Chapman, Peter H. (Peter Henry)
Separation of beam and electrons in the spallation neutron source H{sup -} ion source
The Spallation Neutron Source (SNS) requires an ion source producing an H{sup {minus}} beam with a peak current of 35mA at a 6.2 percent duty factor. For the design of this ion source, extracted electrons must be transported and dumped without adversely affecting the H{sup {minus}} beam optics. Two issues are considered: (1) electron containment transport and controlled removal; and (2) first-order H{sup {minus}} beam steering. For electron containment, various magnetic, geometric and electrode biasing configurations are analyzed. A kinetic description for the negative ions and electrons is employed with self-consistent fields obtained from a steady-state solution to Poisson`s equation. Guiding center electron trajectories are used when the gyroradius is sufficiently small. The magnetic fields used to control the transport of the electrons and the asymmetric sheath produced by the gyrating electrons steer the ion beam. Scenarios for correcting this steering by split acceleration and focusing electrodes will be considered in some detail.
Whealton, J.H.; Raridon, R.J. [Oak Ridge National Lab., TN (United States); Leung, K.N. [Lawrence Berkeley National Lab., CA (United States)
An RF Test Cave has been built at the Spallation Neutron Source (SNS) to be able to test RF cavities without interfering the SNS accelerator operations. In addition to using thick concrete wall to minimize radiation exposure, a Beam Loss Monitor (BLM) must abort the operation within 100 usec when the integrated radiation within the cave exceeds a threshold. We choose the CompactRIO platform to implement the BLM based on its performance, cost-effectiveness, and rapid development. Each in/output module is connected through an FPGA to provide point-by-point processing. Every 10 usec the data is acquired analyzed and compared to the threshold. Data from the FPGA is transferred using DMA to the real-time controller, which communicates to a gateway PC to talk to the SNS control system. The system includes diagnostics to test the hardware and integrates the losses in real-time. In this paper we describe our design, implementation, and results
Blokland, Willem [ORNL; Armstrong, Gary A [ORNL
Producing Persistent, High-Current, High-Duty-Factor H- Beams for Routine 1 MW Operation of SNS
Since 2009, SNS has been producing neutrons with ion beam powers near 1 MW, which requires the extraction of ~50 mA H- ions from the ion source with a ~5% duty factor. The 50 mA are achieved after an initial dose of ~3 mg of Cs and heating the Cs collar to ~170 C. The 50 mA normally persist for the entire 4-week source service cycles. Fundamental processes are reviewed to elucidate the persistence of the SNS H- beams without a steady feed of Cs and why the Cs collar temperature may have to be kept near 170 C.
Stockli, Martin P [ORNL; Han, Baoxi [ORNL; Hardek, Thomas W [ORNL; Kang, Yoon W [ORNL; Murray Jr, S N [ORNL; Pennisi, Terry R [ORNL; Piller, Chip [ORNL; Santana, Manuel [ORNL; Welton, Robert F [ORNL
Novel Large Area High Resolution Neutron Detector for the Spallation Neutron Source
Neutron scattering is a powerful technique that is critically important for materials science and structural biology applications. The knowledge gained from past developments has resulted in far-reaching advances in engineering, pharmaceutical and biotechnology industries, to name a few. New facilities for neutron generation at much higher flux, such as the SNS at Oak Ridge, TN, will greatly enhance the capabilities of neutron scattering, with benefits that extend to many fields and include, for example, development of improved drug therapies and materials that are stronger, longer-lasting, and more impact-resistant. In order to fully realize this enhanced potential, however, higher neutron rates must be met with improved detection capabilities, particularly higher count rate capability in large size detectors, while maintaining practicality. We have developed a neutron detector with the technical and economic advantages to accomplish this goal. This new detector has a large sensitive area, offers 3D spatial resolution, high sensitivity and high count rate capability, and it is economical and practical to produce. The proposed detector technology is based on B-10 thin film conversion of neutrons in long straw-like gas detectors. A stack of many such detectors, each 1 meter in length, and 4 mm in diameter, has a stopping power that exceeds that of He-3 gas, contained at practical pressures within an area detector. With simple electronic readout methods, straw detector arrays can provide spatial resolution of 4 mm FWHM or better, and since an array detector of such form consists of several thousand individual elements per square meter, count rates in a 1 m^2 detector can reach 2?10^7 cps. Moreover, each individual event can be timetagged with a time resolution of less than 0.1 ?sec, allowing accurate identification of neutron energy by time of flight. Considering basic elemental cost, this novel neutron imaging detector can be commercially produced economically, probably at a small fraction of the cost of He-3 detectors. In addition to neutron scattering science, the fully developed base technology can be used as a rugged, low-cost neutron detector in area monitoring and surveying. Radiation monitors are used in a number of other settings for occupational and environmental radiation safety. Such a detector can also be used in environmental monitoring and remote nuclear power plant monitoring. For example, the Department of Energy could use it to characterize nuclear waste dumps, coordinate clean-up efforts, and assess the radioactive contaminants in the air and water. Radiation monitors can be used to monitor the age and component breakdown of nuclear warheads and to distinguish between weapons and reactor grade plutonium. The UN's International Atomic Energy Agency (IAEA) uses radiation monitors for treaty verification, remote monitoring, and enforcing the non-proliferation of nuclear weapons. As part of treaty verification, monitors can be used to certify the contents of containers during inspections. They could be used for portal monitoring to secure border checkpoints, sea ports, air cargo centers, public parks, sporting venues, and key government buildings. Currently, only 2% of all sea cargo shipped is inspected for radiation sources. In addition, merely the presence of radiation is detected and nothing is known about the radioactive source until further testing. The utilization of radiation monitors with neutron sensitivity and capability of operation in hostile port environments would increase the capacity and effectiveness of the radioactive scanning processes.
Lacy, Jeffrey L
Kids' Corner at Neutron Science | ORNL
Center at Fermi National Accelerator Laboratory for use of the atomic mystery model. SNS Activity Book Check out the SNS Activity Book, with information about neutrons and why...
Neutron Production, Moderation, and Characterization of Sources
SNS-TM-2001163. (2002). See section 6.6. 9 J. R. Lamarsh, "Introduction to Nuclear Reactor Theory," Addison Wesley, 1966. See page 168. 10 Ibid, page 186. 11...
SNS - HFIR Users Meeting 2005
Ken Herwig, SNS Jason Hodges, SNS Michael Kent, Sandia Frank Klose, SNS Tonya Kuhl, UC Davis Young Lee, MIT Hanno zur Loye, South Carolina Gary Lynn, HFIR Charles Majkrzak, NIST...
Dr. Georg Ehlers - ORNL Neutron Sciences
Georg Ehlers Georg Ehlers Lead Instrument Scientist: Cold Neutron Chopper Spectrometer (CNCS), SNS Education PhD in Experimental Condensed Matter Physics, the Hahn Meitner Institut, in Berlin, Germany Description of Research Dr. Ehlers joined the Spallation Neutron Source (SNS) in 2003 as the lead instrument scientist for beam line 5, the Cold Neutron Chopper Spectrometer (CNCS). CNCS is a high-resolution, direct geometry, cold neutron, inelastic multi-chopper spectrometer, designed to make use of neutrons with an energy of <50 meV. Before joining the SNS, Dr. Ehlers worked at the Institute Laue-Langevin (ILL), a leading European neutron research facility situated in Grenoble, France for six years. At the ILL, he was instrument-responsible for the spin-echo spectrometers IN11 and IN15, and established a strong research
The First ASME Code Stamped Cryomodule at SNS
The first spare cryomodule for the Spallation Neutron Source (SNS) has been designed, fabricated, and tested by SNS personnel. The approach to design for this cryomodule was to hold critical design features identical to the original design such as bayonet positions, coupler positions, cold mass assembly, and overall footprint. However, this is the first SNS cryomodule that meets the pressure requirements put forth in the 10 CFR 851: Worker Safety and Health Program. The most significant difference is that Section VIII of the ASME Boiler and Pressure Vessel Code was applied to the vacuum vessel of this cryomodule. Applying the pressure code to the helium vessels within the cryomodule was considered. However, it was determined to be schedule prohibitive because it required a code case for materials that are not currently covered by the code. Good engineering practice was applied to the internal components to verify the quality and integrity of the entire cryomodule. The design of the cryomodule, fabrication effort, and cryogenic test results will be reported in this paper.
Howell, M P; Crofford, M T; Douglas, D L; Kim, S -H; Steward, S T; Strong, W H; Afanador, R; Hannah, B S; Saunders, J
The Nanoscale-Ordered Materials Diffractometer at SNS
Samples previously measured with neutrons will not be accepted, even if released by SNS or your local radiation protection officer. 11-ID-B is dedicated to collection of...
Secondary electron ion source neutron generator
A neutron generator employing an electron emitter, an ion source bombarded by the electrons from the electron emitter, a plasma containment zone, and a target situated between the plasma containment zone and the electron emitter. The target contains occluded deuterium, tritium, or a mixture thereof
Brainard, John P. (Albuquerque, NM); McCollister, Daryl R. (Albuquerque, NM)
Cold moderators for pulsed neutron sources
This paper reviews cold moderators in pulsed neutron sources and provides details of the performance of different cold moderator materials and configurations. Analytical forms are presented which describe wavelength spectra and emission time distributions. Several types of cooling arrangements used in pulsed source moderators are described. Choices of materials are surveyed. The author examines some of the radiation damage effects in cold moderators, including the phenomenon of burping'' in irradiated cold solid methane. 9 refs., 15 figs., 4 tabs.
Carpenter, J.M.
VULCAN at the SNS: Scientific Opportunities, Industrial Applications, and
. VULCAN features a unique load-frame allow study of deformation behavior in a complex stress state, including tension-compression, torsion, or multi-axial loading. . VULCAN features a unique load-frame allow study of deformation behavior in a complex stress state, including tension-compression, torsion, or multi-axial loading. VULCAN at the SNS: Scientific Opportunities, Industrial Applications, and Challenges 2. A center piece of VULCAN is the high precision heavy duty sample table, capable of supporting up to 2 ton of industrial sized specimen or sample environment. January 21 - 22, 2010 * Oak Ridge National Laboratory * Oak Ridge, TN, USA Workshop Home Agenda and Important Deadlines Logistics, Hotel, Transportation Committee/Contacts Sponsors Talks Workshop Photos Thank You Note filler VULCAN at the SNS: Scientific Opportunities, Industrial Applications, and Challenges Postworkshop Summary The commissioning of the VULCAN diffractometer at the Spallation Neutron Source presents new and exciting opportunities to engineering diffraction and materials research communities. The idea for an engineering diffractometer at the SNS dates back to a workshop in late 1997, and the desired performance requirements were finalized exactly 10 years ago in a workshop held in Atlanta, Georgia, on January 20-21, 2000. The instrument was funded for construction in November 2003, with a grant from Canada Foundation for Innovation. In August of 2004, the US National Science Foundation Major Research Instrumentation (MRI) Program provided additional funds, through The University of Tennessee, to support unique sample environments for VULCAN. In November 2005, the US Department of Energy, Office of Energy Efficiency and Renewable Energy, funded additional detectors for VULCAN to multiplex the performance of the instrument. VULCAN received first neutrons on Friday June 26, 2009. Initial measurement results show that the neutron flux and instrument resolution are in agreement with Monte Carlo simulations.
Spallation Neutron Source Availability Top-Down Apportionment Using Characteristic Factors and Expert Opinion
Apportionment is the assignment of top-level requirements to lower tier elements of the overall facility. A method for apportioning overall facility availability requirements among systems and subsystems is presented. Characteristics that influence equipment reliability and maintainability are discussed. Experts, using engineering judgment, scored each characteristic for each system whose availability design goal is to be established. The Analytic Hierarchy Process (AHP) method is used to produce a set of weighted rankings for each characteristic for each alternative system. A mathematical model is derived which incorporates these weighting factors. The method imposes higher availability requirements on those systems in which an incremental increase in availability is easier to achieve, and lower availability requirements where greater availability is more difficult and costly. An example is given of applying this top-down apportionment methodology to the Spallation Neutron Source (SNS) facility.
Haire, M.J.; Schryver, J.C.
Physics design of a cold neutron source for KIPT neutron source facility.
Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the conceptual design development of a neutron source facility. It is based on the use of an electron accelerator driven subcritical (ADS) facility with low enriched uranium fuel, using the existing electron accelerators at KIPT of Ukraine [1]. The neutron source of the subcritical assembly is generated from the interaction of 100-KW electron beam, which has a uniform spatial distribution and the electron energy in the range of 100 to 200 MeV, with a natural uranium target [2]. The main functions of the facility are the production of medical isotopes and the support of the Ukraine nuclear power industry. Neutron beam experiments and material studies are also included. Over the past two-three decades, structures with characteristic lengths of 100 {angstrom} and correspondingly smaller vibrational energies have become increasingly important for both science and technology [3]. The characteristic dimensions of the microstructures can be well matched by neutrons with longer vibrational wavelength and lower energy. In the accelerator-driven subcritical facility, most of the neutrons are generated from fission reactions with energy in the MeV range. They are slowed down to the meV energy range through scattering reactions in the moderator and reflector materials. However, the fraction of neutrons with energies less than 5 meV in a normal moderator spectrum is very low because of up-scattering caused by the thermal motion of moderator or reflector molecules. In order to obtain neutrons with energy less than 5 meV, cryogenically cooled moderators 'cold neutron sources' should be used to slow down the neutrons. These cold moderators shift the neutron energy spectrum down because the thermal motion of moderator molecules as well as the up-scattering is very small, which provides large gains in intensity of low energy neutrons, E < 5 meV. The accelerator driven subcritical facility is designed with a provision to add a cryogenically cooled moderator system. This cold neutron source could provide the neutrons beams with lower energy, which could be utilized in scattering experiment and material structures analysis. This study describes the performed physics analyses to define and characterize the cold neutron source of the KIPT neutron source facility. The cold neutron source is designed to optimize the cold neutron brightness to the experimental instruments outside the radial heavy concrete shield of the facility. Liquid hydrogen or solid methane with 20 K temperature is used as a cold moderator. Monte Carlo computer code MCNPX [4], with ENDF/B-VI nuclear data libraries, is utilized to calculate the cold neutron source performance and estimate the nuclear heat load to the cold moderator. The surface source generation capability of MCNPX code has been used to provide the possibility of analyzing different design configurations and perform design optimization analyses with reasonable computer resources. Several design configurations were analyzed and their performance were characterized and optimized.
Zhong, Z.; Gohar, Y.; Kellogg, R.; Nuclear Engineering Division
Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the conceptual design development of a neutron source facility. It is based on the use of an electron accelerator driven subcritical (ADS) facility with low enriched uranium fuel, using the existing electron accelerators at KIPT of Ukraine [1]. The neutron source of the subcritical assembly is generated from the interaction of 100-KW electron beam, which has a uniform spatial distribution and the electron energy in the range of 100 to 200 MeV, with a natural uranium target [2]. The main functions of the facility are the production of medical isotopes and the support of the Ukraine nuclear power industry. Neutron beam experiments and material studies are also included. Over the past two-three decades, structures with characteristic lengths of 100 {angstrom} and correspondingly smaller vibrational energies have become increasingly important for both science and technology [3]. The characteristic dimensions of the microstructures can be well matched by neutrons with longer vibrational wavelength and lower energy. In the accelerator-driven subcritical facility, most of the neutrons are generated from fission reactions with energy in the MeV range. They are slowed down to the meV energy range through scattering reactions in the moderator and reflector materials. However, the fraction of neutrons with energies less than 5 meV in a normal moderator spectrum is very low because of up-scattering caused by the thermal motion of moderator or reflector molecules. In order to obtain neutrons with energy less than 5 meV, cryogenically cooled moderators 'cold neutron sources' should be used to slow down the neutrons. These cold moderators shift the neutron energy spectrum down because the thermal motion of moderator molecules as well as the up-scattering is very small, which provides large gains in intensity of low energy neutrons, E neutron source could provide the neutrons beams with lower energy, which could be utilized in scattering experiment and material structures analysis. This study describes the performed physics analyses to define and characterize the cold neutron source of the KIPT neutron source facility. The cold neutron source is designed to optimize the cold neutron brightness to the experimental instruments outside the radial heavy concrete shield of the facility. Liquid hydrogen or solid methane with 20 K temperature is used as a cold moderator. Monte Carlo computer code MCNPX [4], with ENDF/B-VI nuclear data libraries, is utilized to calculate the cold neutron source performance and estimate the nuclear heat load to the cold moderator. The surface source generation capability of MCNPX code has been used to provide the possibility of analyzing different design configurations and perform design optimization analyses with reasonable computer resources. Several design configurations were analyzed and their performance were characterized and optimized.
Status of R&D on Mitigating the Effects of Pressure Waves for the Spallation Neutron Source Mercury Target
The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory has been conducting R&D on mitigating the effects of pressure waves in mercury spallation targets since 2001. More precisely, cavitation damage of the target vessel caused by the short beam pulse threatens to limit its lifetime more severely than radiation damage as well as limit its ultimate power capacity and hence its neutron intensity performance. The R&D program has moved from verification of the beam-induced damage phenomena to study of material and surface treatments for damage resistance to the current emphasis on gas injection techniques for damage mitigation. Two techniques are being worked on: injection of small dispersed gas bubbles that mitigate the pressure waves volumetrically; and protective gas walls that isolate the vessel from the damaging effects of collapsing cavitation bubbles. The latter has demonstrated good damage mitigation during in-beam testing with limited pulses, and adequate gas wall coverage at the beam entrance window has been demonstrated with the SNS mercury target flow configuration using a full scale mercury test loop. A question on the required area coverage remains which depends on results from SNS target post irradiation examination. The small gas bubble technique has been less effective during past in-beam tests but those results were with un-optimized and un-verified bubble populations. Another round of in-beam tests with small gas bubbles is planned for 2011. The first SNS target was removed from service in mid 2009 and samples were cut from two locations at the target s beam entrance window. Through-wall damage was observed at the innermost mercury vessel wall (not a containment wall). The damage pattern suggested correlation with the local mercury flow condition which is nearly stagnant at the peak damage location. Detailed post irradiation examination of the samples is under way that will assess the erosion and measure irradiation-induced changes in mechanical properties. Similar samples were cut from the second SNS target after it was removed from service in mid 2010. More extensive damage was observed on the target inner wall but damage to the containment wall was minimal.
Riemer, Bernie [ORNL; Wendel, Mark W [ORNL; Felde, David K [ORNL; Abdou, Ashraf A [ORNL; McClintock, David A [ORNL
THE SNS RFQ COMMISSIONING * A. Ratti, J. Ayers, L.on a support structure, and commissioning of the RFQ. Theabout 1.0 dB. BEAM COMMISSIONING RESULTS Beam commissioning
News › 2005 News News › 2005 News Neutron Science In the News - 2005 December November October September August July June May April March February January John Sullivan, Associate Under Secretary, took a tour of the Spallation Neutron Source (SNS), October 4, 2005 John Sullivan, Associate Under Secretary, took a tour of the Spallation Neutron Source (SNS), October 4, 2005. Because some media sources archive past articles and require a subscription for access, some of the links below might not be active. If a citation listed here is no longer available, please contact the newspaper or your library directly. December Spallation Neutron Source Amazing Science Facts Newswise 12/22 The New Year is bringing the science community a grand present: The Spallation Neutron Source at Oak Ridge National Laboratory. On schedule for
ORNL Neutron Sciences Users
SHUG banner SNS-HFIR User Group The SNS-HFIR User Group (SHUG) consists of all persons interested in using the neutron scattering facilities at Oak Ridge. It provides input to the...
Status of the intense pulsed neutron source
IPNS is not unique in having concerns about the level of funding, and the future looks good despite these concerns. This report details the progress made at IPNS during the last two years. Other papers in these proceedings discuss in detail the status of the enriched uranium Booster target, the two instruments that are under construction, GLAD and POSY II, and a proposal for research on an Advanced Pulsed Neutron Source (ASPUN) that has been submitted to the Department of Energy (DOE). Further details on IPNS are available in the IPNS Progress Report 1987--1988, available by writing the IPNS Division Office. 9 refs., 3 tabs.
Brown, B.S.; Carpenter, J.M.; Crawford, R.K.; Rauchas, A.V.; Schulke, A.W.; Worlton, T.G.
EIS-0247: Construction and Operation of the Spallation Neutron Source |
247: Construction and Operation of the Spallation Neutron 247: Construction and Operation of the Spallation Neutron Source EIS-0247: Construction and Operation of the Spallation Neutron Source SUMMARY The United States needs a high-flux, short- pulsed neutron source to provide its scientific and industrial research communities with a much more intense source of pulsed neutrons for neutron scattering research than is currently available. This source would assure the availability of a state-of-the-art neutron research facility in the United States in the decades ahead. This facility would be used to conduct research in areas such as materials science, condensed matter physics, the molecular structure of biological materials, properties of polymers and complex fluids, and magnetism. In addition to creating new scientific and
A compact neutron generator using a field ionization source
in the gas/oil industry radioactive sources are routinelyreplacement of radioactive sources for oil-well logging withto build a neutron source suit- able for oil-well logging
Persaud, Arun
Computational Fluid Dynamics in Support of the SNS Liquid Mercury Thermal-Hydraulic Analysis
Experimental and computational thermal-hydraulic research is underway to support the liquid mercury target design for the Spallation Neutron Source (SNS) facility. The SNS target will be subjected to internal nuclear heat generation that results from pulsed proton beam collisions with the mercury nuclei. Recirculation and stagnation zones within the target are of particular concern because of the likelihood that they will result in local hot spots and diminished heat removal from the target structure. Computational fluid dynamics (CFD) models are being used as a part of this research. Recent improvements to the 3D target model include the addition of the flow adapter which joins the inlet/outlet coolant pipes to the target body and an updated heat load distribution at the new baseline proton beam power level of 2 MW. Two thermal-hydraulic experiments are planned to validate the CFD model.
Siman-Tov, M.; Wendel, M.W.; Yoder, G.L.
rf improvements for Spallation Neutron Source H ion source
The Spallation Neutron Source at Oak Ridge National Laboratory is ramping up the accelerated proton beam power to 1.4 MW and just reached 1 MW. The rf-driven multicusp ion source that originates from the Lawrence Berkeley National Laboratory has been delivering 38 mA H beam in the linac at 60 Hz, 0.9 ms. To improve availability, a rf-driven external antenna multicusp ion source with a water-cooled ceramic aluminum nitride AlN plasma chamber is developed. Computer modeling and simulations have been made to analyze and optimize the rf performance of the new ion source. Operational statistics and test runs with up to 56 mA medium energy beam transport beam current identify the 2 MHz rf system as a limiting factor in the system availability and beam production. Plasma ignition system is under development by using a separate 13 MHz system. To improve the availability of the rf power system with easier maintenance, we tested a 70 kV isolation transformer for the 80 kW, 6% duty cycle 2 MHz amplifier to power the ion source from a grounded solid-state amplifier. 2010 American Institute of Physics.
Kang, Yoon W [ORNL; Fuja, Raymond E [ORNL; Goulding, Richard Howell [ORNL; Hardek, Thomas W [ORNL; Lee, Sung-Woo [ORNL; McCarthy, Mike [ORNL; Piller, Chip [ORNL; Shin, Ki [ORNL; Stockli, Martin P [ORNL; Welton, Robert F [ORNL
Radioactive Neutron Sources Emission Rates (44010C and ...
... Safe handling of neutron sources and the industrial safety aspects are taught through an apprentice-type relationship with each new handler. ...
Neutron Science TeraGrid Gateway
The unique contributions of the Neutron Science TeraGrid Gateway (NSTG) are the connection of national user facility instrument data sources to the integrated cyberinfrastructure of the National Science FoundationTeraGrid and the development of a neutron science gateway that allows neutron scientists to use TeraGrid resources to analyze their data, including comparison of experiment with simulation. The NSTG is working in close collaboration with the Spallation Neutron Source (SNS) at Oak Ridge as their principal facility partner. The SNS is a next-generation neutron source. It has completed construction at a cost of $1.4 billion and is ramping up operations. The SNS will provide an order of magnitude greater flux than any previous facility in the world and will be available to all of the nation's scientists, independent of funding source, on a peer-reviewed merit basis. With this new capability, the neutron science community is facing orders of magnitude larger data sets and is at a critical point for data analysis and simulation. There is a recognized need for new ways to manage and analyze data to optimize both beam time and scientific output. The TeraGrid is providing new capabilities in the gateway for simulations using McStas and a fitting service on distributed TeraGrid resources to improved turnaround. NSTG staff are also exploring replicating experimental data in archival storage. As part of the SNS partnership, the NSTG provides access to gateway support, cyberinfrastructure outreach, community development, and user support for the neutron science community. This community includes not only SNS staff and users but extends to all the major worldwide neutron scattering centers.
Lynch, Vickie E [ORNL; Chen, Meili [ORNL; Cobb, John W [ORNL; Kohl, James Arthur [ORNL; Miller, Stephen D [ORNL; Speirs, David A [ORNL; Vazhkudai, Sudharshan S [ORNL
Neutron Data Analysis and Visualization Division - ORNL Neutron...
develops software and hardware for the reduction and analysis of data taken on SNS and HFIR neutron scattering instruments. We work closely with the SNS and HFIR Data Acquisition...
The Spallation Neutron Source (SNS) Accumulator ring extraction system includes 14 modules of ferrite kicker magnets with window-frame geometry. Among all ring components, the extraction kickers make the single largest contribution to the coupling impedance budget. A prototype was constructed and various design options impacting the transverse coupling impedance have been thoroughly studied. Bench as well as system measurements were performed to determine the benefits from an external circuit resistance, from using different ferrites material, and from adding a novel ferrite winding. The results presented in this paper confirm that a resistive termination in the external circuit yields a solution with sufficiently reduced transverse coupling impedance. In order to determine the total contribution of all modules, an equivalent circuit and a simple scaling law was derived from measurements of full and half size magnets.
A comparison of beam loss in the superconducting part (SCL) of the Spallation Neutron Source (SNS) linac for H- and protons is presented. During the experiment the nominal beam of negative hydrogen ions in the SCL was replaced by a proton beam created by insertion of a thin stripping carbon foil placed in the low energy section of the linac. The observed significant reduction in the beam loss for protons is explained by a domination of the intra beam stripping mechanism of the beam loss for H-. The details of the experiment are discussed, and a preliminary estimation of the cross section of the reaction H- + H- -> H- + H0 + e is presented. Earlier, a short description of these studies was presented in [1].
Aleksandrov, Alexander V [ORNL; Galambos, John D [ORNL; Plum, Michael A [ORNL; Shishlo, Andrei P [ORNL
Optimization of an accelerator-based epithermal neutron source for neutron capture therapy
Nowadays at several nuclear reactors were created BNCTand intensity. Nuclear reactors as neutron source forsource based on a nuclear reactor [4]. The comparison shows
Kononov, O.E.; Kononov, V.N.; Bokhovko, M.V.; Korobeynikov, V.V.; Soloviev, A.N.; Chu, W.T.
High power testing of the 402.5 MHZ and 805 MHZ RF windows for the spallation neutron source accelerator
Hisorically, Radio Frequency (RF) windows have been a common point of failure in input power couplers; therefore, reliable RF windows are critical to the success of the Spallation Neutron Source (SNS) project. The normal conducting part of the SNS accelerator requires six RF windows at 402.5 MHz and eight RF windows at 805 MHz[l]. Each RF window will transmit up to 180 kW of average power and 2.5 MW peak power at 60 Hz with 1.2 millisecond pulses. The RF windows, designed and manufactured by Thales, were tested at the full average power for 4 hours to ensure no problems with the high average power and then tested to an effective forward power level of 10 MW by testing at 2.5 MW forward power into a short and varying the phase of the standing wave. The sliding short was moved from 0 to 180 degrees to ensure no arcing or breakdown problems occur in any part of the window. This paper discusses the results of the high power testing of both the 402.5 MHz and the 805 MHz RF windows. Problems encountered during testing and the solutions for these problems are discussed.
Cummings, K. A. (Karen Ann); De Baca, J. M. (John M.); Harrison, J. S. (John S.); Rodriguez, M. B. (Manuelita B.); Torrez, P. A. (Phillip A.); Warner, D. K. (David K.)
Instrument performance on the short and long pulse second SNS target stations
In this work, we investigate the effect of neutron moderator dimensions on the performance of neutron scattering instruments at the Spallation Neutron Source. In a recent study of the planned second target station at the Spallation Neutron Source (SNS) facility [1,2], we have found that the dimensions of a moderator play a significant role in determining its surface brightness. A smaller moderator may be significantly brighter for a smaller viewing area [4]. One of the immediate implications of this finding is that for modern neutron scattering instrument designs, moderator dimensions and brightness have to be incorporated as an integrated optimization parameter. Here, we establish a strategy of matching neutron scattering instruments with moderators using analytical and Monte Carlo techniques. In order to simplify our treatment, we group the instruments into two broad categories, those with natural collimation and those that use neutron guide systems. We found that the cross-sections of the sample and the neutron guide, respectively, are the deciding factors for choosing the moderator. Beam divergence plays no role as long as it is within the reach of practical constraints. Namely, the required divergence is not too large for the guide or sample to be located close enough to the moderator on an actual spallation source.
Zhao, Jinkui [ORNL; Herwig, Kenneth W [ORNL; Robertson, Lee [ORNL; Gallmeier, Franz X [ORNL; Riemer, Bernie [ORNL
Calculation Package: Derivation of Facility-Specific Derived Air Concentration (DAC) Values in Support of Spallation Neutron Source Operations
Derived air concentration (DAC) values for 175 radionuclides* produced at the Oak Ridge National Laboratory (ORNL) Spallation Neutron Source (SNS), but not listed in Appendix A of 10 CFR 835 (01/01/2009 version), are presented. The proposed DAC values, ranging between 1 E-07 {micro}Ci/mL and 2 E-03 {micro}Ci/mL, were calculated in accordance with the recommendations of the International Commission on Radiological Protection (ICRP), and are intended to support an exemption request seeking regulatory relief from the 10 CFR 835, Appendix A, requirement to apply restrictive DACs of 2E-13 {micro}Ci/mL and 4E-11 {micro}Ci/mL and for non-listed alpha and non-alpha-emitting radionuclides, respectively.
McLaughlin, David A [ORNL
A Fusing Switch for Fault Suppression in the SNS High Voltage Converter Modulators
The High Voltage Converter Modulators (HVCMs) at the Spallation Neutron Source (SNS) have operated in excess of a combined 250,000 hours. Performance and reliability improvements to the HVCM are ongoing to increase modulator availability as accelerator system demands increase. There is a relatively large amount of energy storage in the HVCMs, {approx}180 kJ. This energy has the potential to dump into unsuppressed faults, cause damage, and increase the time to repair. The 'fusing switch' concept involves isolation of this stored energy from the location of the most common faults. This paper introduces this concept and its application to the HVCMs.
Kemp, Mark A.; Burkhart, Craig; Nguyen, Minh N.; /SLAC; Anderson, David E.; /Oak Ridge
Virtual Gamma Ray Radiation Sources through Neutron Radiative Capture
The countrate response of a gamma spectrometry system from a neutron radiation source behind a plane of moderating material doped with a nuclide of a large radiative neutron capture cross-section exhibits a countrate response analogous to a gamma radiation source at the same position from the detector. Using a planar, surface area of the neutron moderating material exposed to the neutron radiation produces a larger area under the prompt gamma ray peak in the detector than a smaller area of dimensions relative to the active volume of the gamma detection system.
Scott Wilde, Raymond Keegan
IMPACT simulation and the SNS linac beam
dynamics studies of the SNS linac systems were performedIMPACT SIMULATION AND THE SNS LINAC BEAM * Y. Zhang 1 , J.tracking simulations for the SNS linac beam dynamics studies
Zhang, Y.
Mechanical design of the SNS MEBT
et al. , �Progress with the SNS Front-End Systems,� PAC �01,T. Saleh, �Design of the SNS MEBT,� Linac �00, Monterey,D.L. Schrage, �Progress with SNS Fast Beam Chopper,� PAC01,
Oshatz, D.; DeMello, A.; Doolittle, L.; Luft, P.; Staples, J.; Zachoszcz, A.
About SNS | ornl.gov
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Neutrons in Biology, ORNL
Scattering Sciences Division Oak Ridge National Laboratory Phone: 865.241.2897 SNS Logo HFIR Logo General Information The unique potential of neutron scattering in structural...
Scattering Sciences Division Oak Ridge National Laboratory Phone: 865.576.2779 SNS Logo HFIR Logo General Information The unique potential of neutron scattering in structural...
Materials Division Oak Ridge National Laboratory Phone: 865.241.5176 SNS Logo HFIR Logo General Information The unique potential of neutron scattering in structural...
ORNL Neutron Sciences Publications
at other facilties by Neutron Sciences Directorate staff. We strongly encourage SNS and HFIR users to submit citation information, including URLs, for all publications regarding...
The design of accelerator components such as magnets, accelerator cavities and beam instruments tends to be a fairly standardized and collective effort within the particle accelerator community with well established performance, reliability and, in some cases, even budgetary criteria. Beam stop design, by contrast, has been comparatively subjective historically with much more general goals. This lack of rigor has lead to a variety of facility implementations with limited standardization and minimal consensus on approach to development within the particle accelerator community. At the Spallation Neutron Source (SNS), for example, there are four high power beam stops in use, three of which have significantly different design solutions. This paper describes the design of a new off-momentum beam stop for the SNS. The technical description of the system will be complemented by a discussion of design methodology. This paper presented an overview of the new SNS HEBT off-momentum beam stop and outlined a methodology for beam stop system design. The new beam stop consists of aluminium and steel blocks cooled by a closed-loop forced-air system and is expected to be commissioned this summer. The design methodology outlined in the paper represents a basic description of the process, data, analyses and critical decisions involved in the development of a beam stop system.
Polsky, Yarom [ORNL; Plum, Michael A [ORNL; Geoghegan, Patrick J [ORNL; Jacobs, Lorelei L [ORNL; Lu, Wei [ORNL; McTeer, Stephen Mark [ORNL
Summary of alpha-neutron sources in GADRAS.
A common source of neutrons for calibration and testing is alpha-neutron material, named for the alpha-neutron nuclear reaction that occurs within. This material contains a long-lived alpha-emitter and a lighter target element. When the alpha particle from the emitter is absorbed by the target, neutrons and gamma rays are released. Gamma Detector Response and Analysis Software (GADRAS) includes built-in alpha-neutron source definitions for AcC, AmB, AmBe, AmF, AmLi, CmC, and PuC. In addition, GADRAS users may create their own alpha-neutron sources by placing valid alpha-emitters and target elements in materials within their one-dimensional models (1DModel). GADRAS has the ability to use pre-built alpha-neutron sources for plotting or as trace-sources in 1D models. In addition, if any material (existing or user-defined) specified in a 1D model contains both an alpha emitter in conjunction with a target nuclide, or there is an interface between such materials, then the appropriate neutron-emission rate from the alpha-neutron reaction will be computed. The gamma-emissions from these sources are also computed, but are limited to a subset of nine target nuclides. If a user has experimental data to contribute to the alpha-neutron gamma emission database, it may be added directly or submitted to the GADRAS developers for inclusion. The gadras.exe.config file will be replaced when GADRAS updates are installed, so sending the information to the GADRAS developers is the preferred method for updating the database. This is also preferable because it enables other users to benefit from your efforts.
Mitchell, Dean James; Thoreson, Gregory G.; Harding, Lee T.
Design of an Aluminum Proton Beam Window for the Spallation Neutron Source
An aluminum proton beam window design is being considered at the Spallation Neutron Source primarily to increase the lifetime of the window, with secondary advantages of higher beam transport efficiency and lower activation. The window separates the core vessel, the location of the mercury target, from the vacuum of the accelerator, while withstanding the pass through of a proton beam of up to 2 MW with 1.0 GeV proton energy. The current aluminum alloy being investigated for the window material is 6061-T651 due to its combination of high strength, high thermal conductivity, and good resistance to aqueous corrosion, as well as demonstrated dependability in previous high-radiation environments. The window design will feature a thin plate with closely spaced cross drilled cooling holes. An analytical approach was used to optimize the dimensions of the window before finite element analysis was used to simulate temperature profiles and stress fields resulting from thermal and static pressure loading. The resulting maximum temperature of 60 C and Von Mises stress of 71 MPa are very low compared to allowables for Al 6061-T651. A significant challenge in designing an aluminum proton beam window for SNS is integrating the window with the current 316L SS shield blocks. Explosion bonding was chosen as a joining technique because of the large bonding area required. A test program has commenced to prove explosion bonding can produce a robust vacuum joint. Pending successful explosion bond testing, the aluminum proton beam window design will be proven acceptable for service in the Spallation Neutron Source.
Janney, Jim G [ORNL; McClintock, David A [ORNL
POWGEN Users | ORNL Neutron Sciences
User Information User Information Announcement: POWGEN has started a new partnership with beam line 11A at the Advanced Photon Source where users can get x-ray data if they have an approved POWGEN proposal. Become a POWGEN User POWGEN Experiment Guide: A - Z POWGEN Mail In Program Guide Shipping Addresses for Samples For more detailed information, please visit the ORNL User Facilities Sample Handling and Shipping page. Non-activated samples coming to SNS: Attention: Special requirements (like refrigeration) To: Neutron Sciences User Sample IPTS # XXXX Oak Ridge National Laboratory / SNS Site Chestnut Ridge, Bldg 8920 Oak Ridge, TN 37830 Activated samples (these will also be brought to SNS but must go through check-in procedures at another on-site location): Attention: Special requirements (like refrigeration)
Compact, energy EFFICIENT neutron source: enabling technology for various applications
A novel neutron source comprising of a deuterium beam (energy of about 100 KeV) injected into a tube filled with tritium gas and/or tritium plasma that generates D-T fusion reactions, whose products are 14.06 MeV neutrons and 3.52 MeV alpha particles, is described. At the opposite end of the tube, the energy of deuterium ions that did not interact is recovered. Beryllium walls of proper thickness can be utilized to absorb 14 MeV neutrons and release 2-3 low energy neutrons. Each ion source and tube forms a module. Larger systems can be formed from multiple units. Unlike currently proposed methods, where accelerator-based neutron sources are very expensive, large, and require large amounts of power for operation, this neutron source is compact, inexpensive, easy to test and to scale up. Among possible applications for this neutron source concept are sub-critical nuclear breeder reactors and transmutation of radioactive waste.
Hershcovitch, A.; Roser, T.
January 16, 2009: Expansion of Spallation Neutron Source
Energy.gov (U.S. Department of Energy (DOE))
January 16, 2009The Department gives its initial approval to begin plans for the Oak Ridge National Laboratory (ORNL) to build a second target station for the Spallation Neutron Source, expanding...
The SNS front-end, an injector for a high-power hydrogen-ion accelerator
The Spallation Neutron Source (SNS) will be an accelerator-based facility in Oak Ridge, TN, delivering pulsed neutron beams to experimenters. Negative hydrogen ion-beams are generated and pre-accelerated in a 2.5-MeV linac injector, or front end (FE), accelerated to 1 GeV energy by a linear accelerator system, converted into protons and accumulated in a ring accelerator, and then directed towards a mercury target to generate the neutrons. The proton beam arrives at the target in bursts of less than 1 {micro}s duration and with more than 1 MW average power. The front end has been built and commissioned by LBNL in Berkeley; shipment to ORNL is essentially complete. This paper provides an overview of FE major design features and experimental results obtained during the commissioning process. The SNS-FE can be viewed as a prototype of a high-current, high duty-factor injector for other accelerator projects or, without the elaborate MEBT, as an independent 2.5-MeV accelerator for various applications.
Keller, R.
Data Analysis & Visualization Division | Neutron Science | ORNL
Optimal Neutron Source and Beam Shaping Assembly for Boron Neutron Capture Therapy
There were three objectives to this project: (1) The development of the 2-D Swan code for the optimization of the nuclear design of facilities for medical applications of radiation, radiation shields, blankets of accelerator-driven systems, fusion facilities, etc. (2) Identification of the maximum beam quality that can be obtained for Boron Neutron Capture Therapy (BNCT) from different reactor-, and accelerator-based neutron sources. The optimal beam-shaping assembly (BSA) design for each neutron source was also to e obtained. (3) Feasibility assessment of a new neutron source for NCT and other medical and industrial applications. This source consists of a state-of-the-art proton or deuteron accelerator driving and inherently safe, proliferation resistant, small subcritical fission assembly.
Vujic, J L; Greenspan, E; Guess, S; Karni, Y; Kastenber, W E; Kim, L; Leung, K N; Regev, D; Verbeke, J M; Waldron, W L; Zhu, Y
A Multi-Dimensional Classification Model for Scientific Workflow Characteristics
13 and 14), SCOOP (Figure 4), SNS (Figure 15), Motif (FigureSpallation Neutron Source (SNS), Neutron Science TeraGridmaterials. Neutron Source SNS at Oak Ridge National
Ramakrishnan, Lavanya
This paper describes the first operational results of the 140 kV, 1 MW average, 11 MW peak, zero-voltage-switching, 20 kHz polyphase bridge, boost converter-modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2100 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three ''H-Bridge'' Insulated Gate Bipolar Transistor (IGBT) switching networks are used to generate the polyphase 20 kHz transformer primary drive waveforms. The 20 kHz drive waveforms are chirped the appropriate duration to generate the desired klystron pulse width. Pulse-Width Modulation (PWM) of the individual 20 kHz pulses is utilized to provide regulated output waveforms with adaptive feedforward and feedback techniques. The boost transformer design utilizes amorphous nanocrystalline material that provides the required low core loss at design flux levels and switching frequencies. Resonant shunt peaking is used on the transformer secondary to boost output voltage and resonate transformer leakage inductance. With the appropriate transformer leakage inductance and peaking capacitance, zero-voltage-switching of the IGBT's is attained, minimizing switching losses. Reviews of these design parameters and an examination of the first operational results will be performed.
Operational results of the spallation neutron source (SNS) polyphase converter-modulator for the 140 KV klystron RF system
This paper describes the first operational results of the 140 kV, 1 MW average, 11 MW peak, zero-voltageswitching, 20 kHz polyphase bridge, boost converter-modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2100 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three 'H-Bridge' Insulated Gate Bipolar Transistor (IGBT) switching networks are used to generate the polyphase 20 kHz transformer primary drive waveforms. The 20 kHz drive waveforms are chirped the appropriate duration to generate the desired klystron pulse width. Pulse-Width Modulation (PWM) of the individual 20 kHz pulses is utilized to provide regulated output waveforms with adaptive feedforward and feedback techniques. The boost transformer design utilizes amorphous nanocrystalline material that provides the required low core loss at design flux levels and switching frequencies. Resonant shunt peaking is used on the transformer secondary to boost output voltage and resonate transformer leakage inductance. With the appropriate transformer leakage inductance and peaking capacitance, zero-voltage-switching of the IGBT's is attained, minimizing switching losses. Reviews of these design parameters and an examination of the first operational results will be performed.
Reass, W. A. (William A.); Doss, James D.; Gribble, R. F. (Robert F.); Lynch, M. T. (Michael T.); Rees, D. E. (Daniel E.); Tallerico, P. J. (Paul J.); Borovina, D. L.
LOW VOLTAGE 14 Mev NEUTRON SOURCE
An apparatus yielding high-energy neutrons at the rate of 10/sup 8/ or more per second by the D,T or D,D reactions is described. The deuterium gas filling is ionized by electrons emitted from a filament, and the resulting ions are focused into a beam and accelerated against a fixed target. The apparatus is built in accordance with the relationship V/sub s/ = A--B log pd, where V/sub s/ is the sparking voltage, p the gas pressure, and d the gap length between the high voltage electrodes. Typical parameters to obtain the high neutron yields are 55 to 80 kv, 0.5 to 7.0 ma beam current, 5 to 12 microns D/sub 2/, and a gap length of 1 centimeter.
Little, R.N. Jr.; Graves, E.R.
07-G00050D/gim SpallationNeutronSource
-4600. Proposals for beam time at Oak Ridge National Laboratory's High Flux Isotope Reactor (HFIR) and Spallation of these instruments. HFIR SNS These facilities are funded by the U.S. Department of Energy. 08-G00986I
Design of an RFQ-Based Neutron Source for Cargo Container Interrogation
blue) vs z. also used in the SNS RFQ [7], which separate theand Initial Testing of the SNS RFQ�, A. Ratti et al,9] �Detailed Modeling of the SNS RFQ Structure with CST Mi-
blue) vs z. also used in the SNS RFQ [8], which separate theand Initial Testing of the SNS RFQ�, A. Ratti et al,10] �Detailed Modeling of the SNS RFQ Structure with CST
Research Highlights | ORNL Neutron Sciences
Research Highlights For all the latest highlights on research at HFIR and SNS, please see the links at left. Featured Research Neutron diffraction reveals semiconducting phase and...
Michael Ohl | ORNL Neutron Sciences
Michael Ohl Lead Instrument Scientist: Neutron Spin Echo Spectrometer (NSE), SNS http:www.jcns.info Education PhD in Physics, University of Augsburg, Germany Description of...
by: Agatha Bardoel Melissa Sharp and Michael Ohl at the Neutron Spin Echo Instrument at SNS. Melissa Sharp, NSE instrument scientist, and ORNL biophysicist Alex Johs at the...
Teacher Programs | ORNL Neutron Sciences
Diffractometer, explains neutron diffractometry to teachers participating in the STARs program. Ashfia Huq (front), instrument scientist for the SNS Powder Diffractometer, explains...
Design considerations for neutron activation and neutron source strength monitors for ITER
The International Thermonuclear Experimental Reactor will require highly accurate measurements of fusion power production in time, space, and energy. Spectrometers in the neutron camera could do it all, but experience has taught us that multiple methods with redundancy and complementary uncertainties are needed. Previously, conceptual designs have been presented for time-integrated neutron activation and time-dependent neutron source strength monitors, both of which will be important parts of the integrated suite of neutron diagnostics for this purpose. The primary goals of the neutron activation system are: to maintain a robust relative measure of fusion energy production with stability and wide dynamic range; to enable an accurate absolute calibration of fusion power using neutronic techniques as successfully demonstrated on JET and TFTR; and to provide a flexible system for materials testing. The greatest difficulty is that the irradiation locations need to be close to plasma with a wide field of view. The routing of the pneumatic system is difficult because of minimum radius of curvature requirements and because of the careful need for containment of the tritium and activated air. The neutron source strength system needs to provide real-time source strength vs. time with {approximately}1 ms resolution and wide dynamic range in a robust and reliable manner with the capability to be absolutely calibrated by in-situ neutron sources as done on TFTR, JT-60U, and JET. In this paper a more detailed look at the expected neutron flux field around ITER is folded into a more complete design of the fission chamber system.
Barnes, C.W. [Los Alamos National Lab., NM (United States); Jassby, D.L.; LeMunyan, G.; Roquemore, A.L. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Walker, C. [ITER Joint Central Team, Garching (Germany)
Subcritical Neutron Multiplication Measurements of HEU Using Delayed Neutrons as the Driving Source
A new method for the determination of the multiplication of highly enriched uranium systems is presented. The method uses delayed neutrons to drive the HEU system. These delayed neutrons are from fission events induced by a pulsed 14-MeV neutron source. Between pulses, neutrons are detected within a medium efficiency neutron detector using {sup 3}He ionization tubes within polyethylene enclosures. The neutron detection times are recorded relative to the initiation of the 14-MeV neutron pulse, and subsequently analyzed with the Feynman reduced variance method to extract singles, doubles and triples neutron counting rates. Measurements have been made on a set of nested hollow spheres of 93% enriched uranium, with mass values from 3.86 kg to 21.48 kg. The singles, doubles and triples counting rates for each uranium system are compared to calculations from point kinetics models of neutron multiplicity to assign multiplication values. These multiplication values are compared to those from MC NP K-Code calculations.
Hollas, C.L.; Goulding, C.A.; Myers, W.L.
Joint Institute for Neutron Sciences | ornl.gov
Joint Institute for Neutron Sciences SHARE Joint Institute for Neutron Sciences JINS is located on Chestnut Ridge within the 80-acre SNS site, part of Oak Ridge National...
Procurement - ORNL Neutron Sciences
for the acquisition of goods and services for neutron scattering operations at SNS and HFIR. If you're interested in conducting business with the Neutron Sciences Directorate or...
Proton Driver Linac for the Frankfurt Neutron Source
The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum (FRANZ) will deliver high neutron fluxes in the energy range of 1 to 500 keV. The Activation Mode provides a high averaged neutron flux created by a cw proton beam of up to 5 mA, while in the Compressor Mode intense neutron pulses of 1 ns length are formed with a repetition rate of up to 250 kHz. The Compressor Mode is well-suited for energy-dependent neutron capture measurements using the Time-of-Flight method in combination with a 4{pi} BaF{sub 2} detector array. The design of the proton driver linac for both operation modes is presented. This includes the volume type ion source, the ExB chopper located in the low energy section, the RFQ-IH combination for beam acceleration and the bunch compressor. Finally, the neutron production at the lithium-7 target and the resulting energy spectrum is described.
Wiesner, C.; Chau, L. P.; Dinter, H.; Droba, M.; Heilmann, M.; Joshi, N.; Maeder, D.; Metz, A.; Meusel, O.; Noll, D.; Podlech, H.; Ratzinger, U.; Reichau, H.; Schempp, A.; Schmidt, S.; Schweizer, W.; Volk, K.; Wagner, C. [Institut fuer Angewandte Physik, Goethe-Universitaet, Max-von-Laue-Str. 1, 60438 Frankfurt/Main (Germany); Reifarth, R. [Institut fuer Angewandte Physik, Goethe-Universitaet, Max-von-Laue-Str. 1, 60438 Frankfurt/Main (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany); Mueller, I.
High Flux Isotope Reactor cold neutron source reference design concept
In February 1995, Oak Ridge National Laboratory`s (ORNL`s) deputy director formed a group to examine the need for upgrades to the High Flux Isotope Reactor (HFIR) system in light of the cancellation of the Advanced neutron Source Project. One of the major findings of this study was that there was an immediate need for the installation of a cold neutron source facility in the HFIR complex. In May 1995, a team was formed to examine the feasibility of retrofitting a liquid hydrogen (LH{sub 2}) cold source facility into an existing HFIR beam tube. The results of this feasibility study indicated that the most practical location for such a cold source was the HB-4 beam tube. This location provides a potential flux environment higher than the Institut Laue-Langevin (ILL) vertical cold source and maximizes the space available for a future cold neutron guide hall expansion. It was determined that this cold neutron beam would be comparable, in cold neutron brightness, to the best facilities in the world, and a decision was made to complete a preconceptual design study with the intention of proceeding with an activity to install a working LH{sub 2} cold source in the HFIR HB-4 beam tube. During the development of the reference design the liquid hydrogen concept was changed to a supercritical hydrogen system for a number of reasons. This report documents the reference supercritical hydrogen design and its performance. The cold source project has been divided into four phases: (1) preconceptual, (2) conceptual design and testing, (3) detailed design and procurement, and (4) installation and operation. This report marks the conclusion of the conceptual design phase and establishes the baseline reference concept.
Selby, D.L.; Lucas, A.T.; Hyman, C.R. [and others
NXS 2010 - Neutron Scattering School
2-26, 2010 2-26, 2010 Argonne National Laboratory, Argonne, IL Oak Ridge National Laboratory, Oak Ridge, TN NXS2010 Travel Airport Shuttles Departure Flights Schedule Participants Lectures Lecturers Lecture Notes/Videos Experiments Schedule, Desc, Groups Student Presentations ANL Facilities APS Facility ANL Map ANL Visitor's Guide ORNL Facilities HFIR Facility SNS Facility HFIR/SNS Map Access Requirements ANL ORNL Rad Worker Training Study Guide Wireless Networks ANL ORNL Safety & Security Rules ANL ORNL NSSA New Initiatives NSSA Weblink Contacts ANL ORNL 12th National School on Neutron & X-ray Scattering 2009 Neutron Scattering School participants 2010 National School Participants Students share their thoughts about NXS 2010. Purpose: The main purpose of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major neutron and x-ray facilities. Lectures, presented by researchers from academia, industry, and national laboratories, will include basic tutorials on the principles of scattering theory and the characteristics of the sources, as well as seminars on the application of scattering methods to a variety of scientific subjects. Students will conduct four short experiments at Argonne's Advanced Photon Source and Oak Ridge's Spallation Neutron Source and High Flux Isotope Reactor facilities to provide hands-on experience for using neutron and synchrotron sources.
Accelerator-based neutron source for boron neutron capture therapy (BNCT) and method
A source for boron neutron capture therapy (BNCT) comprises a body of photoneutron emitter that includes heavy water and is closely surrounded in heat-imparting relationship by target material; one or more electron linear accelerators for supplying electron radiation having energy of substantially 2 to 10 MeV and for impinging such radiation on the target material, whereby photoneutrons are produced and heat is absorbed from the target material by the body of photoneutron emitter. The heavy water is circulated through a cooling arrangement to remove heat. A tank, desirably cylindrical or spherical, contains the heavy water, and a desired number of the electron accelerators circumferentially surround the tank and the target material as preferably made up of thin plates of metallic tungsten. Neutrons generated within the tank are passed through a surrounding region containing neutron filtering and moderating materials and through neutron delimiting structure to produce a beam or beams of epithermal neutrons normally having a minimum flux intensity level of 1.0.times.10.sup.9 neutrons per square centimeter per second. Such beam or beams of epithermal neutrons are passed through gamma ray attenuating material to provide the required epithermal neutrons for BNCT use.
Yoon, Woo Y. (Idaho Falls, ID); Jones, James L. (Idaho Falls, ID); Nigg, David W. (Idaho Falls, ID); Harker, Yale D. (Idaho Falls, ID)
Residual stress measurement using the pulsed neutron source at LANSCE
The presence of residual stress in engineering components can effect their mechanical properties and structural integrity. Neutron diffraction is the only measuring technique which can make spatially resolved non-destructive strain measurements in the interior of components. By recording the change in the crystalline interplanar spacing, elastic strains can be measured for individual lattice reflections. Using a pulsed neutron source, all the lattice reflections are recorded in each measurement which allows anisotropic effects to be studied. Measurements made at the Manuel Lujan Jr Neutron Scattering Centre (LANSCE) demonstrate the potential for stress measurements on a pulsed source and indicate the advantages and disadvantages over measurements made on a reactor. 15 refs., 7 figs.
Bourke, M.A.M.; Goldstone, J.A. (Los Alamos National Lab., NM (USA)); Holden, T.M. (Atomic Energy of Canada Ltd., Chalk River, ON (Canada))
Neutron Scattering Experiment Automation with Python
The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory currently holds the Guinness World Record as the world most powerful pulsed spallation neutron source. Neutrons scattered off atomic nuclei in a sample yield important information about the position, motions, and magnetic properties of atoms in materials. A neutron scattering experiment usually involves sample environment control (temperature, pressure, etc.), mechanical alignment (slits, sample and detector position), magnetic field controllers, neutron velocity selection (choppers) and neutron detectors. The SNS Data Acquisition System (DAS) consists of real-time sub-system (detector read-out with custom electronics, chopper interface), data preprocessing (soft real-time) and a cluster of control and ancillary PCs. The real-time system runs FPGA firmware and programs running on PCs (C++, LabView) typically perform one task such as motor control and communicate via TCP/IP networks. PyDas is a set of Python modules that are used to integrate various components of the SNS DAS system. It enables customized automation of neutron scattering experiments in a rapid and flexible manner. It provides wxPython GUIs for routine experiments as well as IPython command line scripting. Matplotlib and numpy are used for data presentation and simple analysis. We will present an overview of SNS Data Acquisition System and PyDas architectures and implementation along with the examples of use. We will also discuss plans for future development as well as the challenges that have to be met while maintaining PyDas for 20+ different scientific instruments.
Zolnierczuk, Piotr A [ORNL; Riedel, Richard A [ORNL
Design, status and first operations of the spallation neutron source polyphase resonant converter modulator system
The Spallation Neutron Source (SNS) is a new 1.4 MW average power beam, 1 GeV accelerator being built at Oak Ridge National Laboratory. The accelerator requires 15 converter-modulator stations each providing between 9 and 11 MW pulses with up to a 1 .I MW average power. The converter-modulator can be described as a resonant 20 kHz polyphase boost inverter. Each converter modulator derives its buss voltage from a standard substation cast-core transformer. Each substation is followed by an SCR pre-regulator to accommodate voltage changes from no load to full load, in addition to providing a soft-start function. Energy storage is provided by self-clearing metallized hazy polypropylene traction capacitors. These capacitors do not fail short, but clear any internal anomaly. Three 'H-Bridge' IGBT transistor networks are used to generate the polyphase 20 kHz transformer primary drive waveforms. The 20 kHz drive waveforms are time-gated to generate the desired klystron pulse width. Pulse width modulation of the individual 20 lcHz pulses is utilized to provide regulated output waveforms with DSP based adaptive feedforward and feedback techniques. The boost transformer design utilizes nanocrystalline alloy that provides low core loss at design flux levels and switching frequencies. Capacitors are used on the transformer secondary networks to resonate the leakage inductance. The transformers are wound for a specific leakage inductance, not turns ratio. This design technique generates multiple secondary volts per turn as compared to the primary. With the appropriate tuning conditions, switching losses are minimized. The resonant topology has the added benefit of being deQed in a klystron fault condition, with little energy deposited in the arc. This obviates the need of crowbars or other related networks. A review of these design parameters, operational performance, production status, and OWL installation and performance to date will be presented.
Reass, W. A. (William A.); Apgar, S. E. (Sean E.); Baca, D. M. (David M.); Doss, James D.; Gonzales, J. (Jacqueline); Gribble, R. F. (Robert F.); Hardek, T. W. (Thomas W.); Lynch, M. T. (Michael T.); Rees, D. E. (Daniel E.); Tallerico, P. J. (Paul J.); Trujillo, P. B. (Pete B.); Anderson, D. E. (David E.); Heidenreich, D. A. (Dale A.); Hicks, J. D. (Jim D.); Leontiev, V. N.
the end of May to make up for lost ground. Operations manager Kevin Jones said the SNS resumed operations for research users at about 8 a.m. on Tuesday. "SNS is operating at...
Design of a High Intensity Neutron Source for Neutron-Induced Fission Yield Studies
The upgraded IGISOL facility with JYFLTRAP, at the accelerator laboratory of the University of Jyv\\"askyl\\"a, has been supplied with a new cyclotron which will provide protons of the order of 100 {\\mu}A with up to 30 MeV energy, or deuterons with half the energy and intensity. This makes it an ideal place for measurements of neutron-induced fission products from various actinides, in view of proposed future nuclear fuel cycles. The groups at Uppsala University and University of Jyv\\"askyl\\"a are working on the design of a neutron converter that will be used as neutron source in fission yield studies. The design is based on simulations with Monte Carlo codes and a benchmark measurement that was recently performed at The Svedberg Laboratory in Uppsala. In order to obtain a competitive count rate the fission targets will be placed very close to the neutron converter. The goal is to have a flexible design that will enable the use of neutron fields with different energy distributions. In the present paper, some considerations for the design of the neutron converter will be discussed, together with different scenarios for which fission targets and neutron energies to focus on.
M. Lantz; D. Gorelov; A. Jokinen; V. S. Kolhinen; A. Mattera; H. Penttil�; S. Pomp; V. Rakopoulos; S. Rinta-Antila; A. Solders
Performance of the intense pulsed neutron source accelerator system
The Intense Pulsed Neutron Source (IPNS) facility has now been operating in a routine way for outside users since November 1, 1981. From that date through December of 1982, the accelerator system was scheduled for neutron science for 4500 hours. During this time the accelerator achieved its short-term goals by delivering about 380,000,000 pulses of beam totaling over 6 x 10/sup 20/ protons. The changes in equipment and operating practices that evolved during this period of intense running are described. The intensity related instability threshold was increased by a factor of two and the accelerator beam current has been ion source limited. Plans to increase the accelerator intensity are also described. Initial operating results with a new H/sup -/ ion source are discussed.
Potts, C.; Brumwell, F.; Rauchas, A.; Stipp, V.; Volk, G.
Surface plasma source with saddle antenna radio frequency plasma generator
A prototype RF H{sup -} surface plasma source (SPS) with saddle (SA) RF antenna is developed which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with small AlN discharge chambers and different antennas and magnetic field configurations were tested in the plasma source test stand. A prototype SA SPS was installed in the Spallation Neutron Source (SNS) ion source test stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency up to 1.6 mA/kW. Control experiments with H{sup -} beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma gun has been designed. A saddle antenna SPS with water cooling is fabricated for high duty factor testing.
Dudnikov, V.; Johnson, R. P. [Muons, Inc., Batavia, Illinios 60510 (United States); Murray, S.; Pennisi, T.; Piller, C.; Santana, M.; Stockli, M.; Welton, R. [ORNL, Oak Ridge, Tennessee 37831 (United States)
A field evaporation deuterium ion source for neutron generators
Proof-of-principle experiments have demonstrated an electrostatic field evaporation based deuterium ion source for use in compact, high-output deuterium-tritium neutron generators. The ion source produces principally atomic deuterium and titanium ions. More than 100 monolayers of deuterated titanium thin film can be removed and ionized from a single tip in less than 20 ns. The measurements indicate that with the use of microfabricated tip arrays the deuterium ion source could provide sufficient ion current to produce 10^9 to 10^10 n/cm^2 of tip array area.
Reichenbach, Birk; Schwoebel, P R; 10.1063/1.2913331
A status report on the Advanced Neutron Source Project
The Advanced Neutron Source (ANS) will be a new laboratory for neutron research, centered around a 330 MW(f) research reactor cooled and reflected by heavy water and including extensive experiment systems and support facilities. The major components of the baseline design, occupying about 16 heetares, are a guide hall/research support area, containing most of the neutron beam experiment systems, shops and supporting laboratories; a 60 m diameter containment building housing the reactor and its primary coolant system, and selected scientific research facilities; an operations support building with the majority of the remaining plant systems; an office/interface complex providing a carefully designed, user friendly entry point for access control; and several other major facilities including user housing, an electrical substation, a diesel generator building, a cryorefrigerator building, and heavy water cleanup and upgrade systems.
West, C.D.
Dense Plasma Focus Fusion Neutron Sources Progress at NSTec, September 2011
A number of dense plasma focus (DPF) sources are introduced, including their operating characteristics and current activities. Neutron resonance spectroscopy is discussed and the feasibility of using DPF for neutron sources is considered.
Hagen, E. C.
SNS Target Systems Operational
scheduling conflict with other remote handling work planned for the next shutdown. · The target and PBW integrated monolith and hot cell structures #12;32 Managed by UT-Battelle for the U.S. Department of Energy based on testing at Riken to 1.8 x 105 Gy · Improved neutronic performance and reduced remote handling
McDonald, Kirk
R&D Status for In-Situ Plasma Surface Cleaning of SRF Cavities at Spallation Neutron Source
The SNS SCL is reliably operating at 0.93 GeV output energy with an energy reserve of 10MeV with high availability. Most of the cavities exhibit field emission, which directly or indirectly (through heating of end groups) limits the gradients achievable in the high beta cavities in normal operation with the beam. One of the field emission sources would be surface contaminations during surface processing for which mild surface cleaning, if any, will help in reducing field emission. An R&D effort is in progress to develop in-situ surface processing for the cryomodules in the tunnel without disassembly. As the first attempt, in-situ plasma processing has been applied to the CM12 in the SNS SRF facility after the repair work with a promising result. This paper will report the R&D status of plasma processing in the SNS.
S.-H. Kim, M.T. Crofford, M. Doleans, J.D. Mammosser, J. Saunders
A hybrid ion-source concept for a proton driver front-end
Results Ob- tained with the SNS H - Ion Source and LEBT atLaboratory, Berkeley, CA, USA SNS at Oak Ridge Nationalat moderate energy into an SNS- type multi-cusp H - ion
News & Events - ORNL Neutron Sciences
0 News 0 News Neutron Science In the News - 2000 December November October September August July June May April March February January Because some media sources archive past articles and require a subscription for access, some of the links below might not be active. If a citation listed here is no longer available, please contact the newspaper or your library directly. December Construction trade program graduates first class Oak Ridger, 12/19 Lawrence T. Young, president and chief executive officer of CROET, "Apprenticeships and pre-apprenticeship programs ensure East Tennesseans have access to the economic opportunities that are opening up at SNS." SNS Holds Construction Job Fair Dec. 20 Oak Ridger, 12/19 The Spallation Neutron Source project is sponsoring a construction worker
Education | ORNL Neutron Sciences
Education banner Education banner Sunil Sinha A Chat with Sunil Sinha, Distinguished Professor of Physics at the University of California-San Diego and speaker at the recent CNMS-SNS Research Forum more... The purpose of the Spallation Neutron Source and the High Flux Isotope Reactor is to facilitate neutron scattering as an integral tool for scientific research and technological development across many scientific and engineering domains within the scientific, academic,and industrial communities. Coupled with this role is a recognized need to inspire, educate, and facilitate the next generation of users and hence foster enhanced use of the unique neutron scattering facilities at ORNL. This is the central theme of the education activities within the Neutron Sciences Directorate (NScD).
Neutron Powder Diffraction Workshop (NPD2011)
Workshop Contact Information Instructors Application Form Sample Description HB2A at HFIR POWGEN at SNS filler About the Workshop Neutron powder diffraction is a widely used...
Neutron Data Analysis & Visualization | More Science | ORNL
the data sets generated by the increasingly powerful neutron scattering instruments at HFIR and SNS grow ever more massive, the facilities' users require significant advances in...
ORNL Neutron Sciences Instrument Fact Sheets
of each neutron scattering instrument at ORNL. You can also view SNS Instrument and HFIR Instrument pages that go to the related instrument's web pages. Detailed information...
Quantum Condensed Matter Division | Neutron Science | ORNL
instruments used for diffraction and inelastic neutron scattering at both SNS and HFIR. The science conducted by our staff members emphasizes materials with emergent...
Publications and Resources | Neutron Science | ORNL
ORNL facilities by Neutron Science Directorate staff. We strongly encourage SNS and HFIR users to submit citation information, including URLs, for all publications regarding...
Chemical and Engineering Materials | Neutron Science | ORNL
Materials SHARE Chemical and Engineering Materials Neutron-based research at SNS and HFIR in Chemical and Engineering Materials strives to understand the structure and dynamics...
ORNL Neutron Scattering User Meeting (ONSUM 2011)
and learning about the capabilities of neutron scattering instruments at SNS and HFIR Meeting fellow user scientists and engineers to discuss ongoing research and R&D needs...
Neutron Instruments Added at Oak Ridge
The neutron scattering facilities at Oak Ridge National Laboratory continue their development as new instruments are commissioned and join the user program at the Spallation Neutron Source and High Flux Isotope Reactor. More than 640 proposals were received for beam time during the January-May 2011 period on SNS and HFIR instruments with about half either being accepted or identified as alternates. The proposal call for the period June-December 2011, announced at http://neutrons.ornl.gov, will close February 23, 2011.
RF Distribution System for High Power Test of the SNS Cryomodule
A four-way waveguide RF power distribution system for testing the Spallation Neutron Source (SNS) multi-cavity cryomodule to investigate the collective behavior has been developed. A single klystron operating at 805MHz for 1.3 msec at 60Hz powers the 4-way waveguide splitter to deliver up to 400 kW to individual cavities. Each cavity is fed through a combination of waveguide splitters and vector modulators (VM) to provide independent magnitude and phase controls. The waveguide vector modulator consists of two quadrature hybrids and two motorized waveguide phase shifters. The phase shifters and the assembled waveguide vector modulators were individually tested and characterized for low power and high RF power in the SNS RF test facility. Precise calibrations of magnitude and phase were performed to generate the look up tables (LUTs) to provide operational references during the cryomodule test. An I-Q demodulator module was developed and utilized to measure relative phases in pulsed high RF power operation. PLC units were developed for mechanical control of the phase shifters. Initial low/high power measurements were made using LabVIEW. An operation algorithm has been implemented into EPICS control for the cryomodule test stand.
Lee, Sung-Woo [ORNL; Kang, Yoon W [ORNL; Broyles, Michael R [ORNL; Crofford, Mark T [ORNL; Geng, Xiaosong [ORNL; Kim, Sang-Ho [ORNL; Phibbs, Curtis L [ORNL; Strong, William Herb [ORNL; Peglow, Robert C [ORNL; Vassioutchenko, Alexandre V [ORNL
The advanced neutron source research and development plan
The Advanced Neutron Source (ANS) is being designed as a user-oriented neutron research laboratory centered around the most intense continuous beams of thermal and subthermal neutrons in the world (an order of magnitude more intense than beams available from the most advanced existing reactors). The ANS will be built around a new research reactor of 330-MW fission power, producing an unprecedented peak thermal flux of >7 {center_dot} 10{sup 19} {center_dot} m{sup -2} {center_dot} s{sup -1}. Primarily a research facility, the ANS will accommodate more than 1000 academic, industrial, and government researchers each year. They will conduct basic research in all branches of science as well as applied research leading to better understanding of new materials, including high temperature super conductors, plastics, and thin films. Some 48 neutron beam stations will be set up in the ANS beam rooms and the neutron guide hall for neutron scattering and for fundamental and nuclear physics research. There also will be extensive facilities for materials irradiation, isotope production, and analytical chemistry. The top level work breakdown structure (WBS) for the project. As noted in this figure, one component of the project is a research and development (R&D) program (WBS 1.1). This program interfaces with all of the other project level two WBS activities. Because one of the project guidelines is to meet minimum performance goals without relying on new inventions, this R&D activity is not intended to produce new concepts to allow the project to meet minimum performance goals. Instead, the R&D program will focus on the four objectives described.
Selby, D.L.
Neutron Science User Program
provides a user gateway for SNS and HFIR 11 Managed by UT-Battelle for the U.S. Department of Energy #12.) · Complementary to SNS HFIR produces the world's highest thermal neutron flux #12;13 UT-Battelle Department infrastructure (REDC, HFIR, etc.): $3B+ national asset ORNL is uniquely positioned to support advanced nuclear
SNS Parameters List - SNS 100000000-PL0001-R13
5 5 SNS 100000000-PL0001-R13 SNS Parameters List This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and
Towards Understanding the Cesium Cycle of the Persistent H{sup -} Beams at SNS
This paper describes the accomplishments of the SNS H{sup -} ion source, which delivers routinely {approx}50 mA at a 5.4% duty factor with {approx}99% availability, enabling 1 MW beams for neutron production with {approx}90% availability. It discusses the need for increasing reliability and beam current. But mostly it focuses on its unexpected feature: H{sup -} beams that are apparently persistent for up to 5 weeks without adding Cs after an initial dose of less than {approx}5 mg. Thermal emission and sputtering are qualitatively evaluated, and appear consistent with a negligible Cs sputter rate after the initial dose disappears from the Cs plasma. It concludes with a list of future experiments that can shed more light on this apparently unique Cs cycle.
Stockli, Martin P.; Han, B. X.; Murray, S. N.; Pennisi, T. R.; Santana, M.; Welton, R. F. [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)
Neutron source in the MCNPX shielding calculating for electron accelerator driven facility
Argonne National Laboratory (ANL) of USA and Kharkov Inst. of Physics and Technology (KIPT) of Ukraine have been collaborating on the design development of an experimental neutron source facility. It is an accelerator driven system (ADS) utilizing a subcritical assembly driven by electron accelerator. The facility will be utilized for performing basic and applied nuclear researches, producing medical isotopes, and training young nuclear specialists. Monte Carlo code MCNPX has been utilized as a design tool due to its capability to transport electrons, photons, and neutrons at high energies. However the facility shielding calculations with MCNPX need enormous computational resources and the small neutron yield per electron makes sampling difficulty for the Monte Carlo calculations. A method, based on generating and utilizing neutron source file, was proposed and tested. This method reduces significantly the required computer resources and improves the statistics of the calculated neutron dose outside the shield boundary. However the statistical errors introduced by generating the neutron source were not directly represented in the results, questioning the validity of this methodology, because an insufficiently sampled neutron source can cause error on the calculated neutron dose. This paper presents a procedure for the validation of the generated neutron source file. The impact of neutron source statistic on the neutron dose is examined by calculating the neutron dose as a function of the number of electron particles used for generating the neutron source files. When the value of the calculated neutron dose converges, it means the neutron source has scored sufficient records and statistic does not have apparent impact on the calculated neutron dose. In this way, the validity of neutron source and the shield analyses could be verified. (authors)
Zhong, Z.; Gohar, Y. [Nuclear Engineering Div., Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)
A SEARCH FOR POINT SOURCES OF EeV NEUTRONS
A thorough search of the sky exposed at the Pierre Auger Cosmic Ray Observatory reveals no statistically significant excess of events in any small solid angle that would be indicative of a flux of neutral particles from a discrete source. The search covers from -90 Degree-Sign to +15 Degree-Sign in declination using four different energy ranges above 1 EeV (10{sup 18} eV). The method used in this search is more sensitive to neutrons than to photons. The upper limit on a neutron flux is derived for a dense grid of directions for each of the four energy ranges. These results constrain scenarios for the production of ultrahigh energy cosmic rays in the Galaxy.
Abreu, P.; Andringa, S. [LIP and Instituto Superior Tecnico, Technical University of Lisbon (Portugal); Aglietta, M. [Istituto di Fisica dello Spazio Interplanetario (INAF), Universita di Torino and Sezione INFN, Torino (Italy); Ahlers, M. [University of Wisconsin, Madison, WI (United States); Ahn, E. J. [Fermilab, Batavia, IL (United States); Albuquerque, I. F. M. [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, SP (Brazil); Allard, D. [Laboratoire AstroParticule et Cosmologie (APC), Universite Paris 7, CNRS-IN2P3, Paris (France); Allekotte, I. [Centro Atomico Bariloche and Instituto Balseiro (CNEA-UNCuyo-CONICET), San Carlos de Bariloche (Argentina); Allen, J. [New York University, New York, NY (United States); Allison, P. [Ohio State University, Columbus, OH (United States); Almela, A. [Facultad Regional Buenos Aires, Universidad Tecnologica Nacional, Buenos Aires (Argentina); Alvarez Castillo, J. [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico); Alvarez-Muniz, J. [Universidad de Santiago de Compostela (Spain); Alves Batista, R. [IFGW, Universidade Estadual de Campinas, Campinas, SP (Brazil); Ambrosio, M.; Aramo, C. [Universita di Napoli 'Federico II' and Sezione INFN, Napoli (Italy); Aminaei, A. [IMAPP, Radboud University Nijmegen (Netherlands); Anchordoqui, L. [University of Wisconsin, Milwaukee, WI (United States); Antici'c, T. [Rudjer Boskovi'c Institute, 10000 Zagreb (Croatia); Arganda, E. [IFLP, Universidad Nacional de La Plata and CONICET, La Plata (Argentina); Collaboration: Pierre Auger Collaboration; and others
Materials Selection for the HFIR Cold Neutron Source
In year 2002 the High Flux Isotope Reactor (HFIR) will be fitted with a source of cold neutrons to upgrade and expand its existing neutron scattering facilities. The in-reactor components of the new source consist of a moderator vessel containing supercritical hydrogen gas moderator at a temperature of 20K and pressure of 15 bar, and a surrounding vacuum vessel. They will be installed in an enlarged beam tube located at the site of the present horizontal beam tube, HB-4; which terminates within the reactor's beryllium reflector. These components must withstand exceptional service conditions. This report describes the reasons and factors underlying the choice of 6061-T6 aluminum alloy for construction of the in-reactor components. The overwhelming considerations are the need to minimize generation of nuclear heat and to remove that heat through the flowing moderator, and to achieve a minimum service life of about 8 years coincident with the replacement schedule for the beryllium reflector. 6061-T6 aluminum alloy offers the best combination of low nuclear heating, high thermal conductivity, good fabricability, compatibility with hydrogen, superior cryogenic properties, and a well-established history of satisfactory performance in nuclear environments. These features are documented herein. An assessment is given of the expected performance of each component of the cold source.
Farrell, K.
Neutrons from the SNS's target are channeled
provide analytical data that enable researchers to determine the atomic and molecular structures's just completed SING project. #12;The history of the city of Oak Ridge and its federal facilities dates back almost 70 years. Now an oral history program focused on recording the memories of city residen
Results of the SNS front end commissioning at Berkeley Lab
RESULTS OF THE SNS FRONT END COMMISSIONING AT BERKELEY LAB *USA A. Aleksandrov for the SNS Accelerator Physics Group andT. Shea for the SNS Beam Diagnostics Collaboration Oak Ridge
Progress with the SNS front-end systems
47317 PROGRESS WITH THE SNS FRONT-END SYSTEMS* R. Keller,**the FES Team, �Status of the SNS Front-End Sys- tems, Paperof the LEBT Layout for SNS,� Paper MOD19, Linac 2000,
SNS_03.31.10.pdf | Department of Energy
SNS03.31.10.pdf SNS03.31.10.pdf SNS03.31.10.pdf More Documents & Publications LCLS.pdf EIS-0247: Draft Environmental Impact Statement Audit Report: OAS-L-05-05...
Neutron source capability assessment for cumulative fission yields measurements
A recent analysis of high-quality cumulative fission yields data for Pu-239 published in the peer-reviewed literature showed that the quoted experimental uncertainties do not allow a clear statement on how the fission yields vary as a function of energy. [Prussin2009] To make such a statement requires a set of experiments with well 'controlled' and understood sources of experimental errors to reduce uncertainties as low as possible, ideally in the 1 to 2% range. The Inter Laboratory Working Group (ILWOG) determined that Directed Stockpile Work (DSW) would benefit from an experimental program with the stated goal to reduce the measurement uncertainties significantly in order to make a definitive statement of the relationship of energy dependence to the cumulative fission yields. Following recent discussions between Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL), there is a renewed interest in developing a concerted experimental program to measure fission yields in a neutron energy range from thermal energy (0.025 eV) to 14 MeV with an emphasis on discrete energies from 0.5 to 4 MeV. Ideally, fission yields would be measured at single energies, however, in practice there are only 'quasi-monoenergetic' neutrons sources of finite width. This report outlines a capability assessment as of June 2011 of available neutron sources that could be used as part of a concerted experimental program to measure cumulative fission yields. In a framework of international collaborations, capabilities available in the United States, at the Atomic Weapons Establishment (AWE) in the United Kingdom and at the Commissariat Energie Atomique (CEA) in France are listed. There is a need to develop an experimental program that will reduce the measurement uncertainties significantly in order to make a definitive statement of the relationship of energy dependence to the cumulative fission yields. Fission and monoenergetic neutron sources are available that could support these fission yield experiments in the US, as well as at AWE and CEA. Considerations that will impact the final choice of experimental venues are: (1) Availability during the timeframe of interest; (2) Ability to accommodate special nuclear materials; (3) Cost; (4) Availability of counting facilities; and (5) Expected experimental uncertainties.
Descalle, M A; Dekin, W; Kenneally, J
Advanced Neutron Source (ANS) Project. Progress report FY 1993
This report covers the progress made in 1993 in the following sections: (1) project management; (2) research and development; (3) design and (4) safety. The section on research and development covers the following: (1) reactor core development; (2) fuel development; (3) corrosion loop tests and analysis; (4) thermal-hydraulic loop tests; (5) reactor control and shutdown concepts; (6) critical and subcritical experiments; (7) material data, structure tests, and analysis; (8) cold source development; (9) beam tube, guide, and instrument development; (10) neutron transport and shielding; (11) I and C research and development; and (12) facility concepts.
Campbell, J.H. [ed.; Selby, D.L.; Harrington, R.M. [Oak Ridge National Lab., TN (United States); Thompson, P.B. [Martin Marietta Energy Systems, Inc., Oak Ridge, TN (United States). Engineering Div.
Field ionization as a means to create ions for compact and rugged neutron sources is pursued. Arrays of carbon nano-#12;bers promise the high #12;eld-enhancement factors required for efficient field ionization. We report on the fabrication of arrays of #12;field emitters with a density up to 10{sup 6} tips/cm{sup 2} and measure their performance characteristics using electron field emission. The critical issue of uniformity is discussed, as are efforts towards coating the nano-fibers to enhance their lifetime and surface properties.
Persaud, Arun; Waldmann, Ole; Kapadia, Rehan; Takei, Kuniharu; Javey, Ali; Schenkel, Thomas
5 MW pulsed spallation neutron source, Preconceptual design study
This report describes a self-consistent base line design for a 5 MW Pulsed Spallation Neutron Source (PSNS). It is intended to establish feasibility of design and as a basis for further expanded and detailed studies. It may also serve as a basis for establishing project cost (30% accuracy) in order to intercompare competing designs for a PSNS not only on the basis of technical feasibility and technical merit but also on the basis of projected total cost. The accelerator design considered here is based on the objective of a pulsed neutron source obtained by means of a pulsed proton beam with average beam power of 5 MW, in {approx} 1 {mu}sec pulses, operating at a repetition rate of 60 Hz. Two target stations are incorporated in the basic facility: one for operation at 10 Hz for long-wavelength instruments, and one operating at 50 Hz for instruments utilizing thermal neutrons. The design approach for the proton accelerator is to use a low energy linear accelerator (at 0.6 GeV), operating at 60 Hz, in tandem with two fast cycling booster synchrotrons (at 3.6 GeV), operating at 30 Hz. It is assumed here that considerations of cost and overall system reliability may favor the present design approach over the alternative approach pursued elsewhere, whereby use is made of a high energy linear accelerator in conjunction with a dc accumulation ring. With the knowledge that this alternative design is under active development, it was deliberately decided to favor here the low energy linac-fast cycling booster approach. Clearly, the present design, as developed here, must be carried to the full conceptual design stage in order to facilitate a meaningful technology and cost comparison with alternative designs.
Not Available
Mechanical Design and Analysis of a 200 MHz, Bolt-together RFQ for the Accelerator Driven Neutron Source
Duty Factor RFQ for the SNS,� EPAC '00, Vienna, Austria, pp.at LBNL, including for the SNS Front End [3]. The use ofused successfully on the SNS RFQ, requires that the vane
Virostek, Steve; Hoff, Matt; Li, Derun; Staples, John; Wells, Russell
Demonstration of a solid deuterium source of ultra-cold neutrons
Ultra-cold neutrons (UCN), neutrons with energies low enough to be confined by the Fermi potential in material bottles, are playing an increasing role in measurements of fundamental properties of the neutron. The ability to manipulate UCN with material guides and bottles, magnetic fields, and gravity can lead to experiments with lower systematic errors than have been obtained in experiments with cold neutron beams. The UCN densities provided by existing reactor sources limit these experiments. The promise of much higher densities from solid deuterium sources has led to proposed facilities coupled to both reactor and spallation neutron sources. In this paper we report on the performance of a prototype spallation neutron-driven solid deuterium source. This source produced bottled UCN densities of 145 +/-7 UCN/cm3, about three times greater than the largest bottled UCN densities previously reported. These results indicate that a production UCN source with substantially higher densities should be possible.
A. Saunders; J. M. Anaya; T. J. Bowles; B. W. Filippone; P. Geltenbort; R. E. Hill; M. Hino; S. Hoedl; G. E. Hogan; T. M. Ito; K. W. Jones; T. Kawai; K. Kirch; S. K. Lamoreaux; C. -Y. Liu; M. Makela; L. J. Marek; J. W. Martin; C. L. Morris; R. N. Mortensen; A. Pichlmaier; S. J. Seestrom; A. Serebrov; D. Smith; W. Teasdale; B. Tipton; R. B. Vogelaar; A. R. Young; J. Yuan
Neutrons for Catalysis: A Workshop on Neutron Scattering Techniques for Studies in Catalysis
This report summarizes the Workshop on Neutron Scattering Techniques for Studies in Catalysis, held at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) on September 16 and 17, 2010. The goal of the Workshop was to bring experts in heterogeneous catalysis and biocatalysis together with neutron scattering experimenters to identify ways to attack new problems, especially Grand Challenge problems in catalysis, using neutron scattering. The Workshop locale was motivated by the neutron capabilities at ORNL, including the High Flux Isotope Reactor (HFIR) and the new and developing instrumentation at the SNS. Approximately 90 researchers met for 1 1/2 days with oral presentations and breakout sessions. Oral presentations were divided into five topical sessions aimed at a discussion of Grand Challenge problems in catalysis, dynamics studies, structure characterization, biocatalysis, and computational methods. Eleven internationally known invited experts spoke in these sessions. The Workshop was intended both to educate catalyst experts about the methods and possibilities of neutron methods and to educate the neutron community about the methods and scientific challenges in catalysis. Above all, it was intended to inspire new research ideas among the attendees. All attendees were asked to participate in one or more of three breakout sessions to share ideas and propose new experiments that could be performed using the ORNL neutron facilities. The Workshop was expected to lead to proposals for beam time at either the HFIR or the SNS; therefore, it was expected that each breakout session would identify a few experiments or proof-of-principle experiments and a leader who would pursue a proposal after the Workshop. Also, a refereed review article will be submitted to a prominent journal to present research and ideas illustrating the benefits and possibilities of neutron methods for catalysis research.
Overbury, Steven {Steve} H [ORNL; Coates, Leighton [ORNL; Herwig, Kenneth W [ORNL; Kidder, Michelle [ORNL
Light in the dark; the new German neutron source FRM-II for ...
... Light in the dark; the new German neutron source FRM-II for science, medicine and industry. Winfried Petry, ZWE FRM-II ...
Chemical and Engineering Materials Division | ORNL Neutron Sciences
and Engineering Materials Division (CEMD) supports neutron-based research at SNS and HFIR in understanding the structure and dynamics of chemical systems and novel engineering...
Data Acquisition System - Instrument Support | ORNL Neutron Sciences
Acquisition & Controls The RAD Instrument Data Acquisition and Controls Group supports SNS neutron instruments by designing, building and maintaining custom electronics and...
Nanoscale-Ordered Materials Diffractometer Nanoscale-Ordered Materials Diffractometer Inside the NOMAD detector tank. Inside the NOMAD detector tank. NOMAD is a high-flux, medium-resolution diffractometer that uses a large bandwidth of neutron energies and extensive detector coverage to carry out structural determinations of local order in crystalline and amorphous materials. It enables studies of a large variety of samples ranging from liquids, solutions, glasses, polymers, and nanocrystalline materials to long-range-ordered crystals. The enhanced neutron flux at SNS, coupled with the advanced neutron optics and detector features of NOMAD, allows for unprecedented access to high-resolution pair distribution functions, small-contrast isotope substitution experiments, small sample sizes, and parametric studies.
Advanced Neutron Source (ANS) Project progress report, FY 1994
The President`s budget request for FY 1994 included a construction project for the Advanced Neutron Source (ANS). However, the budget that emerged from the Congress did not, and so activities during this reporting period were limited to continued research and development and to advanced conceptual design. A significant effort was devoted to a study, requested by the US Department of Energy (DOE) and led by Brookhaven National Laboratory, of the performance and cost impacts of reducing the uranium fuel enrichment below the baseline design value of 93%. The study also considered alternative core designs that might mitigate those impacts. The ANS Project proposed a modified core design, with three fuel elements instead of two, that would allow operation with only 50% enriched uranium and use existing fuel technology. The performance penalty would be 15--20% loss of thermal neutron flux; the flux would still just meet the minimum design requirement set by the user community. At the time of this writing, DOE has not established an enrichment level for ANS, but two advisory committees have recommended adopting the new core design, provided the minimum flux requirements are still met.
Campbell, J.H.; King-Jones, K.H. [eds.; Selby, D.L.; Harrington, R.M. [Oak Ridge National Lab., TN (United States); Thompson, P.B. [Martin Marietta Energy Systems, Inc., Oak Ridge, TN (United States). Central Engineering Services
Conceptual design of a high-intensity positron source for the Advanced Neutron Source
The Advanced Neutron Source (ANS) is a planned new basic and applied research facility based on a powerful steady-state research reactor that provides neutrons for measurements and experiments in the fields of materials science and engineering, biology, chemistry, materials analysis, and nuclear science. The useful neutron flux will be at least five times more than is available in the world`s best existing reactor facility. Construction of the ANS provides a unique opportunity to build a positron spectroscopy facility (PSF) with very-high-intensity beams based on the radioactive decay of a positron-generating isotope. The estimated maximum beam current is 1000 to 5000 times higher than that available at the world`s best existing positron research facility. Such an improvement in beam capability, coupled with complementary detectors, will reduce experiment durations from months to less than one hour while simultaneously improving output resolution. This facility will remove the existing barriers to the routine use of positron-based analytical techniques and will be a giant step toward realization of the full potential of the application of positron spectroscopy to materials science. The ANS PSF is based on a batch cycle process using {sup 64}Cu isotope as the positron emitter and represents the status of the design at the end of last year. Recent work not included in this report, has led to a proposal for placing the laboratory space for the positron experiments outside the ANS containment; however, the design of the positron source is not changed by that relocation. Hydraulic and pneumatic flight tubes transport the source material between the reactor and the positron source where the beam is generated and conditioned. The beam is then transported through a beam pipe to one of several available detectors. The design presented here includes all systems necessary to support the positron source, but the beam pipe and detectors have not been addressed yet.
Hulett, L.D.; Eberle, C.C.
Commissioning of the new high-intensity ultracold neutron source at the Paul Scherrer Institut
Commissioning of the new high-intensity ultracold neutron (UCN) source at the Paul Scherrer Institut (PSI) has started in 2009. The design goal of this new generation high intensity UCN source is to surpass by a factor of ~100 the current ultracold neutron densities available for fundamental physics research, with the greatest thrust coming from the search for a neutron electric dipole moment. The PSI UCN source is based on neutron production via proton induced lead spallation, followed by neutron thermalization in heavy water and neutron cooling in a solid deuterium crystal to cold and ultracold energies. A successful beam test with up to 2 mA proton beam on the spallation target was conducted recently. Most source components are installed, others being finally mounted. The installation is on the track for the first cool-down and UCN production in 2010.
Bernhard Lauss
Physics @ Oxford SCATTERING NEUTRONS
1 Neutron Scattering Society of America (NSSA) Purpose and New Initiatives www.neutronscattering.org SNS/ANL School on Neutron and X-Ray Scattering June 2011 Visit us now on Facebook #12;2 What is the NSSA? NSSA is an organization of scientists and engineers with a common interest in using neutron
Herz, Laura M.
Spallation-Driven Cold Neutron Sources Dr. Bradley J. Micklich
, et al. "Direct observation of fermion spin superposition by neutron interferometry," Physical ReviewNeutron Interferometry with Polarized Spin States Frank Rioux Department of Chemistry CSB|SJU The following paragraph appears in an encyclopedia entry on neutron optics.(1) A description of the original
Breast Tissue Imaging | ORNL Neutron Sciences
Neutron scattering measures samples too hot to hold Neutron scattering measures samples too hot to hold Research Contact: Kenneth Kelton August 2013 Liquids and glasses can have unique optical, electronic, and structural applications but are poorly understood compared to crystalline materials, limiting the ability to take advantage of the characteristics of glasses in a range of applications. Containers can react with molten samples at high temperatures or can favor the growth of crystals over the formation of glasses. Using the chemical and isotopic sensitivity of neutron scattering to understand these disordered structures requires a new capability to hold samples in a neutron beam at high temperature without using a solid physical container. New sample environment equipment at Oak Ridge National Laboratory's (ORNL) Spallation Neutron Source (SNS) enables scientists to
Mechanical design considerations of a spherical torus volumetric neutron source
The mechanical design of a spherical torus based volumetric neutron source (ST VNS) is being studied under the support of a DOE-SBIR funding. A device capable of staged operation from a neutron wall loading of 0.5-5.0 MW/m(2) has been scoped out, as the physics and engineering design assumptions are raised from modest to aggressive levels. Margins in the design are ensured since operation of the VNS will be adequate st a wall loading of 2 MW/m(2). The device has a naturally diverted plasma with major radius of 1.07 m, a minor radius of 0.77 m for an aspect ratio of 1.4, an elongation of 3 and triangularity of 0,6. In the neutral beam driven version, the plasma current is 11.1 MA and the toroidal field at the plasma major radius is 2.13 T, The baseline fusion power is 151 MW giving an average neutron wall loading of 2 MV/m(2) on the outboard side over an accessible area of over 15 m(2) for blanket testing. The device utilizes a normal Cu conducting bell jar as the return leg of the toroidal field current, a concept developed at the Oak Ridge National Laboratory. The current is carried by an unshielded single-turn center post (CP) made of dispersion strengthened Cu which is cooled by water in a single pass from top to bottom. A special sliding electrical interface between the CP and the bell jar is provided on the upper end to allow for differential expansion and to isolate the CP from tensile and torsional forces from the bell jar. The ohmic heating in the CP is 153 MW at the start of operation and increases to 178 MW after 3 full power years of operation. Over this period the maximum Cu temperature does not exceed 160 C. This report primarily deals with the design of the CP, one of the most challenging Issues of a low aspect ratio spherical torus. Maintenance approaches for the Or and the divertor assemblies have been determined and are addressed in the paper.
Sviatoslavky, I. N. [University of Wisconsin, Madison; Peng, Yueng Kay Martin [ORNL
Use of the WNR spallation neutron source at LAMPF to determine the absolute efficiency of a neutron scintillation detector
Prompt fission neutron spectrum measurements at the University of Massachusetts Lowell 5.5 MV Van de Graaff accelerator laboratory require that the neutron detector efficiency be well known over a neutron energy range of 100 keV to 20 MeV. The efficiency of the detector, has been determined for energies greater than 5.0 MeV using the Weapons Neutron Research (WNR) white neutron source at the Los Alamos Meson Physics Facility (LAMPF) in a pulsed beam, time-of-flight (TOF) experiment. Carbon matched polyethylene and graphite scatterers were used to obtain a hydrogen spectrum. The detector efficiency was determined using the well known H(n,n) scattering cross section. Results are compared to the detector efficiency calculation program SCINFUL available from the Radiation Shielding Information Center at Oak Ridge National Laboratory.
Staples, P.A.; Egan, J.J.; Kegel, G.H.R.; Woodring, M.L.; DeSimone, D.J. [University of Massachusetts, Lowell, MA (United States). Dept. of Physics and Applied Physics; Lisowski, P.W. [Los Alamos National Lab., NM (United States)
2010 Neutron Review: ORNL Neutron Sciences Progress Report
During 2010, the Neutron Sciences Directorate focused on producing world-class science, while supporting the needs of the scientific community. As the instrument, sample environment, and data analysis tools at High Flux Isotope Reactor (HFIR ) and Spallation Neutron Source (SNS) have grown over the last year, so has promising neutron scattering research. This was an exciting year in science, technology, and operations. Some topics discussed are: (1) HFIR and SNS Experiments Take Gordon Battelle Awards for Scientific Discovery - Battelle Memorial Institute presented the inaugural Gordon Battelle Prizes for scientific discovery and technology impact in 2010. Battelle awards the prizes to recognize the most significant advancements at national laboratories that it manages or co-manages. (2) Discovery of Element 117 - As part of an international team of scientists from Russia and the United States, HFIR staff played a pivotal role in the discovery by generating the berkelium used to produce the new element. A total of six atoms of ''ununseptium'' were detected in a two-year campaign employing HFIR and the Radiochemical Engineering Development Center at Oak Ridge National Laboratory (ORNL) and the heavy-ion accelerator capabilities at the Joint Institute for Nuclear Research in Dubna, Russia. The discovery of the new element expands the understanding of the properties of nuclei at extreme numbers of protons and neutrons. The production of a new element and observation of 11 new heaviest isotopes demonstrate the increased stability of super-heavy elements with increasing neutron numbers and provide the strongest evidence to date for the existence of an island of enhanced stability for super-heavy elements. (3) Studies of Iron-Based High-Temperature Superconductors - ORNL applied its distinctive capabilities in neutron scattering, chemistry, physics, and computation to detailed studies of the magnetic excitations of iron-based superconductors (iron pnictides and chalcogenides), a class of materials discovered in 2008. This research is yielding new insights into the relationship between magnetism and superconductivity and has established several key features of this family of high-temperature superconducting (HTS ) materials: the maximum magnetic field at which they can function, the nature of the electrons involved in the superconductivity, the dependence of the properties upon chemical substitution, and the character of the magnetic fluctuations in the material. The results suggest that despite important differences between these materials and the HTS copper oxides, a universal mechanism may be responsible for the unconventional superconductivity. (4) Coal Sequestration Research: A New Home for Greenhouse Gases - One possibility for slowing down the increasing levels of carbon dioxide (CO{sub 2}) in the atmosphere is to capture the gas in natural underground features such as coal seams. Critical to the feasibility of this technology is determining how much CO{sub 2} can be stored, no method for which has been found - until now. (5) Accelerator Reliability Passes 92% - In December 2010, SNS set a new record for itself when the accelerator ran at 1 MW with 100% reliability. Target Performance Exceeds All Expectations - The mercury target used at SNS is the first of its kind. During the design and planning for SNS, many people were skeptical that the target would work. In 2010, it was confirmed that the target was working not only well but much better than anyone would have imagined. (6) Changing the World of Data Acquisition - Researchers at SNS are starting to benefit from event-based data analysis. Event data mode captures and stores an individual data set for every single neutron that strikes a detector - precisely when and where the neutron is detected. This technique provides numerous advantages over traditional methods. Event data mode allows researchers to process their data at the highest resolution possible with no loss of data. This method of data collection provides a much more efficient way for users to gather data a
Bardoel, Agatha A [ORNL; Counce, Deborah Melinda [ORNL; Ekkebus, Allen E [ORNL; Horak, Charlie M [ORNL; Nagler, Stephen E [ORNL; Kszos, Lynn A [ORNL
SNS electrical systems have been operational for 4 years. System availability statistics and improvements are presented for AC electrical systems, DC and pulsed power supplies and klystron modulators.
Cutler, Roy I [ORNL; Peplov, Vladimir V [ORNL; Wezensky, Mark W [ORNL; Norris, Kevin Paul [ORNL; Barnett, William E [ORNL; Hicks, Jim [ORNL; Weaver, Joey T [ORNL; Moss, John [ORNL; Rust, Kenneth R [ORNL; Mize, Jeffery J [ORNL; Anderson, David E [ORNL
rf improvements for Spallation Neutron Source H{sup -} ion source
The Spallation Neutron Source at Oak Ridge National Laboratory is ramping up the accelerated proton beam power to 1.4 MW and just reached 1 MW. The rf-driven multicusp ion source that originates from the Lawrence Berkeley National Laboratory has been delivering {approx}38 mA H{sup -} beam in the linac at 60 Hz, 0.9 ms. To improve availability, a rf-driven external antenna multicusp ion source with a water-cooled ceramic aluminum nitride (AlN) plasma chamber is developed. Computer modeling and simulations have been made to analyze and optimize the rf performance of the new ion source. Operational statistics and test runs with up to 56 mA medium energy beam transport beam current identify the 2 MHz rf system as a limiting factor in the system availability and beam production. Plasma ignition system is under development by using a separate 13 MHz system. To improve the availability of the rf power system with easier maintenance, we tested a 70 kV isolation transformer for the 80 kW, 6% duty cycle 2 MHz amplifier to power the ion source from a grounded solid-state amplifier.
Kang, Y. W.; Fuja, R.; Hardek, T.; Lee, S.-W.; McCarthy, M. P.; Piller, M. C.; Shin, K.; Stockli, M. P.; Welton, R. F. [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Goulding, R. H. [Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
Control system for the Spallation Neutron Source H{sup -} source test facility Allison scanner
Spallation Neutron Source is currently in progress of a multiyear plan to ramp ion beam power to the initial design power of 1.4 MW. Key to reaching this goal is understanding and improving the operation of the H{sup -} ion source. An Allison scanner was installed on the ion source in the test facility to support this improvement. This paper will discuss the hardware and the software control system of the installed Allison scanner. The hardware for the system consists of several parts. The heart of the system is the scanner head, complete with associated bias plates, slits, and signal detector. There are two analog controlled high voltage power supplies to bias the plates in the head, and a motor with associated controller to position the head in the beam. A multifunction data acquisition card reads the signals from the signal detector, as well as supplies the analog voltage control for the power supplies. To synchronize data acquisition with the source, the same timing signal that is used to trigger the source itself is used to trigger data acquisition. Finally, there is an industrial personal computer to control the rest of the hardware. Control software was developed using National Instruments LABVIEW, and consists of two parts: a data acquisition program to control the hardware and a stand alone application for offline user data analysis.
Long, C. D.; Stockli, M. P.; Gorlov, T. V.; Han, B.; Murray, S. N.; Pennisi, T. R. [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States)
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Media banner News & Media New SNS Power Record Achieved: 1.4 MW Xiaoguang Hao Click the image to download the video. Examples of Nondestructive Examination Using Neutron Imaging...
Californium-252: neutron source for industry and medicine
From eleventh conference on radioisotopes; Tokyo, Japan (13 Nov 1973). The history, production, and availability of /sup 252/Cf and its many potential uses are discussed. Applications in life sciences, education chemical analysis, exploration for natural resources, industrial process control, neutron radiography, nondestructive inspection, and neutron flux enhancement are described. (TFD)
Reinig, W.C.; Permar, P.H.; Cornman, W.R.
BINP accelerator based epithermal neutron source V. Aleynik a
medical physics to Homeland security. Summary: Neutrons are a powerful tool for the identificationImaging Technique for a Neutron Based Elemental Analysis Interrogation System D. S. Koltick* and I. S. Novikov Purdue University, Physics Department and Center for Sensing Science and Technology 525
201 MHz Cavity R&D for MUCOOL and MICE
Spallation Neutron Source (SNS). This work was supported byRF windows developed for the SNS adjusted by deforming the
Feasibility studies of an accelerator for the intense pulsed neutron source (IPNS)
A proton linac plus synchrotron system was studied for the proposed Intense Pulsed Neutron Source (IPNS) at Argonne. An Alvarez H$sup -$ linac of 70 MeV and a high intensity fast cycling proton synchrotron to accelerate protons to 800 MeV will be the best choice to give a flux of 10$sup 16$ thermal neutron/sec cm$sup 2$ at the surface of moderator with a spallation neutron target of W or $sup 238$U. (auth)
Khoe, T.K.; Kimura, M.
Powder diffraction in materials science using the KENS cold-neutron source
Since superconductivity fever spread around the world, neutron powder diffraction has become very popular and been widely used by crystallographers, physicists, chemists, mineralogists, and materials scientists. The purpose of present paper is to show, firstly, important characteristics of time-of-flight TOF powder diffraction using cold-neutron source in the study of materials science, and, secondly, recent studies on the structure and function of batteries at the Neutron Science Laboratory (KENS) in the High Energy Accelerator Research Organization (KEK).
Kamiyama, T.; Oikawa, K. [Univ. of Tsukuba (Japan). Inst. of Materials Science; Akiba, E. [National Inst. of Materials and Chemical Research, Tsukuba (Japan)] [and others
A laser-induced repetitive fast neutron source applied for gold activation analysis
A laser-induced repetitively operated fast neutron source was developed for applications in laser-driven nuclear physics research. The developed neutron source, which has a neutron yield of approximately 4 Multiplication-Sign 10{sup 5} n/pulse and can be operated up to a pulse repetition rate of 10 Hz, was applied for a gold activation analysis. Relatively strong delayed gamma spectra of the activated gold were measured at 333 keV and 355 keV, and proved the possibility of the neutron source for activation analyses. In addition, the nuclear reactions responsible for the measured gamma spectra of gold were elucidated by the 14 MeV fast neutrons resulting from the D(t,n)He{sup 4} nuclear reaction, for which the required tritium originated from the primary fusion reaction, D(d,p)T{sup 3}.
Lee, Sungman; Park, Sangsoon; Lee, Kitae; Cha, Hyungki [Quantum Optics Division, Korea Atomic Energy Research Institute, Daejeon 305-600 (Korea, Republic of)
Intense Pulsed Neutron Source progress report for 1991
The IPNS Progress Report 10th Anniversary Edition is being published in recognition of the first ten years of successful IPNS operation. To emphasize the significance of this milestone, we wanted this report to stand apart from the previous IPNS Progress Reports, and the best way to do this, we thought, was to make the design and organization of the report significantly different. In their articles, authors were asked to emphasize not only advances made since IPNS began operating but also the groundwork that was laid at its predecessor facilities - Argonne's ZING-P and ZING-P' prototype pulsed neutron sources and CP-5 reactor. Each article stands as a separate chapter in the report, since each represents a particular instrument or class of instruments, system, technique, or area of research. In some cases, contributions were similar to review articles in scientific journals, complete with extensive lists of references. Ten-year cumulative lists of members of IPNS committees and of scientists who have visited or done experiments at IPNS were assembled. A list of published and in press'' articles in journals, books, and conference proceedings, resulting from work done at IPNS during the past ten years, was compiled. And archival photographs of people and activities during the ten-year history of IPNS were located and were used liberally throughout the report. The titles of the chapters in this report are: accelerator; computer; radiation effects; powder; stress; single crystal; superconductivity; amorphous; small angle; reflection; quasielastic; inelastic; inelastic magnetic; deep inelastic; user program; the future; and publications.
The IPNS Progress Report 10th Anniversary Edition is being published in recognition of the first ten years of successful IPNS operation. To emphasize the significance of this milestone, we wanted this report to stand apart from the previous IPNS Progress Reports, and the best way to do this, we thought, was to make the design and organization of the report significantly different. In their articles, authors were asked to emphasize not only advances made since IPNS began operating but also the groundwork that was laid at its predecessor facilities - Argonne`s ZING-P and ZING-P` prototype pulsed neutron sources and CP-5 reactor. Each article stands as a separate chapter in the report, since each represents a particular instrument or class of instruments, system, technique, or area of research. In some cases, contributions were similar to review articles in scientific journals, complete with extensive lists of references. Ten-year cumulative lists of members of IPNS committees and of scientists who have visited or done experiments at IPNS were assembled. A list of published and ``in press`` articles in journals, books, and conference proceedings, resulting from work done at IPNS during the past ten years, was compiled. And archival photographs of people and activities during the ten-year history of IPNS were located and were used liberally throughout the report. The titles of the chapters in this report are: accelerator; computer; radiation effects; powder; stress; single crystal; superconductivity; amorphous; small angle; reflection; quasielastic; inelastic; inelastic magnetic; deep inelastic; user program; the future; and publications.
Fabrication and characterization of the source grating for visibility improvement of neutron phase imaging with gratings
The fabrication of gratings including metal deposition processes for highly neutron absorbing lines is a critical issue to achieve a good visibility of the grating-based phase imaging system. The source grating for a neutron Talbot-Lau interferometer is an array of Gadolinium (Gd) structures that are generally made by sputtering, photo-lithography, and chemical wet etching. However, it is very challenging to fabricate a Gd structure with sufficient neutron attenuation of approximately more than 20 {mu}m using a conventional metal deposition method because of the slow Gd deposition rate, film stress, high material cost, and so on. In this article, we fabricated the source gratings for neutron Talbot-Lau interferometers by filling the silicon structure with Gadox particles. The new fabrication method allowed us a very stable and efficient way to achieve a much higher Gadox filled structure than a Gd film structure, and is even more suitable for thermal polychromatic neutrons, which are more difficult to stop than cold neutrons. The newly fabricated source gratings were tested at the polychromatic thermal neutron grating interferometer system of HANARO at the Korea Atomic Energy Research Institute, and the visibilities and images from the neutron phase imaging system with the new source gratings were compared with those fabricated by a Gd deposition method.
Kim, Jongyul [Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Nuclear and Quantum Engineering Department, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); Lee, Kye Hong; Lim, Chang Hwy; Kim, Taejoo [Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Ahn, Chi Won [Nano Fusion Technology Division, National Nanofab Center, Daejeon 305-701 (Korea, Republic of); Cho, Gyuseong [Nuclear and Quantum Engineering Department, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); Lee, Seung Wook [School of Mechanical Engineering, Pusan National University, Pusan 609-735 (Korea, Republic of)
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Biology and Soft Matter | Neutron Sciences | ORNL
Biology and Soft Matter Biology and Soft Matter SHARE Biology and Soft Matter This is a time of unprecedented opportunity for using neutrons in biological and soft matter research. The US Department of Energy (DOE) has invested in two forefront neutron user facilities, the accelerator-based Spallation Neutron Source (SNS) and the reactor-based High Flux Isotope Reactor (HFIR), at Oak Ridge National Laboratory (ORNL). Researchers have access to new instrumentation on some of the world's most intense neutron beam lines for studying the structure, function, and dynamics of complex systems. We anticipate that soft matter and biological sciences of tomorrow will require understanding, predicting, and manipulating complex systems to produce the new materials and products required to meet our nation's
2821/2000/62#9#/092005#6#/$15.00 ©2000 The American Physical Society 62 0920051 #12; II. EXPERIMENT The measurement of the neutron and the singleneutron event is shown in the top panel of Fig. F. BOEHM et al. PHYSICAL REVIEW D 62 092005 092005 and # 2 are displayed. NEUTRON PRODUCTION BY COSMICRAY MUONS AT . . . PHYSICAL REVIEW D 62 092005 092005
Designing and testing the neutron source deployment system and calibration plan for a dark matter detector
In this thesis, we designed and tested a calibration and deployment system for the MiniCLEAN dark matter detector. The deployment system uses a computer controlled winch to lower a canister containing a neutron source into ...
Westerdale, Shawn (Shawn S.)
Proceedings of the 10th meeting of the international collaboration on advanced neutron sources
This report contains papers from the 10th meeting of the International Collaboration on Advanced Neutron Sources. Two general types of workshops are discussed, instrument and target-station. Individual papers are indexed separately elsewhere. (LSP)
Hyer, D.K. (comp. and ed.)
Instruments | Neutron Science | ORNL
NScD Careers NScD Careers Supporting Organizations Neutron Science Home | Science & Discovery | Neutron Science | Instruments SHARE Instruments at SNS and HFIR SNS Instrument Name HFIR Instrument Name 1B NOMAD - Nanoscale-Ordered Materials Diffractometer CG-1 Development Beam Line 2 BASIS - Backscattering Spectrometer CG-1D IMAGING - Neutron Imaging Prototype Facility 3 SNAP - Spallation Neutrons and Pressure Diffractometer CG-2 GP-SANS - General-Purpose Small-Angle Neutron Scattering Diffractometer 4A MR - Magnetism Reflectometer CG-3 Bio-SANS - Biological Small-Angle Neutron Scattering Instrument 4B LR - Liquids Reflectometer CG-4C CTAX - Cold Neutron Triple-Axis Spectrometer 5 CNCS - Cold Neutron Chopper Spectrometer HB-1 PTAX - Polarized Triple-Axis Spectrometer
Microstructural Evolution of SnS Thin Films Grown by ...
About this Abstract. Meeting, 2012 TMS Annual Meeting & Exhibition. Symposium , Energy Nanomaterials. Presentation Title, Microstructural Evolution of SnS�...
Computational and Experimental Validation of a WGPu Neutron Leakage Source Using a Shielded PuBe (,n) Neutron Source
Neutron Measurements / Special Issue on the 11th International Conference on Radiation Shielding and the 15th Topical Meeting of the Radiation Protection and Shielding Division (Part 2) / Radiation Protection
Gabriel Ghita; Glenn Sjoden; James Baciak
A collaborative learning service for SNS in ubiquitous computing environment
In this paper, we propose a SNS-based collaborative learning service in ubiquitous environment. The point is it supports the learner to get help from the other SNS members, at the end makes them help each other. The service allowed the users use the ... Keywords: KA, SNS, mobile computing, ubiquitous computing
Chengjiu Yin; Yoshiyuki Tabata; Hiroaki Ogata
The development of solid methane neutron moderators at the Intense Pulsed Neutron Source facility of Argonne National Laboratory.
The Intense Pulsed Neutron Source (IPNS) started using solid methane moderators in 1985 because of their efficient conversion (about 3.5 times greater than was achieved with a liquid hydrogen moderator) of fast neutrons to long wavelength neutrons. However, the solid methane moderators experienced numerous failures due to pressure surges caused by a combination of (1) the release of stored energy, which occurred when methane radiolytic products recombined, and (2) the expansion of hydrogen, which built up in the solid methane during irradiation. During the ensuing years studies were made to determine how to operate the solid methane moderators without causing failure. The rate at which stored energy built up during irradiation and the temperature at which hydrogen was released during annealing were determined. Since 1993 IPNS has successfully operated the solid methane moderators (at about 30 K) by periodically annealing to the liquid state around 90 K after every roughly three days of irradiation.
Carpenter, J. M.; Miller, M. E.; Scott, T. L.
A workshop on enhanced national capability for neutron scattering
This two-day workshop will engage the international neutron scattering community to vet and improve the Lujan Center Strategic Plan 2007-2013 (SP07). Sponsored by the LANL SC Program Office and the University of California, the workshop will be hosted by LANSCE Professor Sunny Sinha (UCSD). Endorsement by the Spallation Neutron Source will be requested. The discussion will focus on the role that the Lujan Center will play in the national neutron scattering landscape assuming full utilization of beamlines, a refurbished LANSCE, and a 1.4-MW SNS. Because the Lujan Strategic Plan is intended to set the stage for the Signature Facility era at LANSCE, there will be some discussion of the long-pulse spallation source at Los Alamos. Breakout groups will cover several new instrument concepts, upgrades to present instruments, expanded sample environment capabilities, and a look to the future. The workshop is in keeping with a request by BES to update the Lujan strategic plan in coordination with the SNS and the broader neutron community. Workshop invitees will be drawn from the LANSCE User Group and a broad cross section of the US, European, and Pacific Rim neutron scattering research communities.
Hurd, Alan J [Los Alamos National Laboratory; Rhyne, James J [Los Alamos National Laboratory; Lewis, Paul S [Los Alamos National Laboratory
Secondary Startup Neutron Sources as a Source of Tritium in a Pressurized Water Reactor (PWR) Reactor Coolant System (RCS)
The hypothesis of this paper is that the Zircaloy clad fuel source is minimal and that secondary startup neutron sources are the significant contributors of the tritium in the RCS that was previously assigned to release from fuel. Currently there are large uncertainties in the attribution of tritium in a Pressurized Water Reactor (PWR) Reactor Coolant System (RCS). The measured amount of tritium in the coolant cannot be separated out empirically into its individual sources. Therefore, to quantify individual contributors, all sources of tritium in the RCS of a PWR must be understood theoretically and verified by the sum of the individual components equaling the measured values.
Shaver, Mark W.; Lanning, Donald D.
Rationale for a spallation neutron source target system test facility at the 1-MW Long-Pulse Spallation Source
The conceptual design study for a 1-MW Long-Pulse Spallation Source at the Los Alamos Neutron Science Center has shown the feasibility of including a spallation neutron test facility at a relatively low cost. This document presents a rationale for developing such a test bed. Currently, neutron scattering facilities operate at a maximum power of 0.2 MW. Proposed new designs call for power levels as high as 10 MW, and future transmutation activities may require as much as 200 MW. A test bed will allow assessment of target neutronics; thermal hydraulics; remote handling; mechanical structure; corrosion in aqueous, non-aqueous, liquid metal, and molten salt systems; thermal shock on systems and system components; and materials for target systems. Reliable data in these areas are crucial to the safe and reliable operation of new high-power facilities. These tests will provide data useful not only to spallation neutron sources proposed or under development, but also to other projects in accelerator-driven transmutation technologies such as the production of tritium.
Sommer, W.F.
Monte Carlo modeling and analyses of YALINA- booster subcritical assembly Part II : pulsed neutron source.
One of the most reliable experimental methods for measuring the kinetic parameters of a subcritical assembly is the Sjoestrand method applied to the reaction rate generated from a pulsed neutron source. This study developed a new analytical methodology for characterizing the kinetic parameters of a subcritical assembly using the Sjoestrand method, which allows comparing the analytical and experimental time dependent reaction rates and the reactivity measurements. In this methodology, the reaction rate, detector response, is calculated due to a single neutron pulse using MCNP/MCNPX computer code or any other neutron transport code that explicitly simulates the fission delayed neutrons. The calculation simulates a single neutron pulse over a long time period until the delayed neutron contribution to the reaction is vanished. The obtained reaction rate is superimposed to itself, with respect to the time, to simulate the repeated pulse operation until the asymptotic level of the reaction rate, set by the delayed neutrons, is achieved. The superimposition of the pulse to itself was calculated by a simple C computer program. A parallel version of the C program is used due to the large amount of data being processed, e.g. by the Message Passing Interface (MPI). The new calculation methodology has shown an excellent agreement with the experimental results available from the YALINA-Booster facility of Belarus. The facility has been driven by a Deuterium-Deuterium or Deuterium-Tritium pulsed neutron source and the (n,p) reaction rate has been experimentally measured by a {sup 3}He detector. The MCNP calculation has utilized the weight window and delayed neutron biasing variance reduction techniques since the detector volume is small compared to the assembly volume. Finally, this methodology was used to calculate the IAEA benchmark of the YALINA-Booster experiment.
Talamo, A.; Gohar, M. Y. A.; Rabiti, C.; Nuclear Engineering Division
Note: A portable pulsed neutron source based on the smallest sealed-type plasma focus device
Development and operation of a portable and compact pulsed neutron source based on sealed-type plasma focus (PF) device are reported. The unit is the smallest sealed-type neutron producing PF device. The effective volume of the PF unit is 33 cm{sup 3} only. A compact size single capacitor (4 {mu}F) is used as the energy driver. A battery based power supply unit is used for charging the capacitor and triggering the spark gap. The PF unit is operated at 10 kV (200 J) and at a deuterium gas filling pressure of 8 mb. The device is operated over a time span of 200 days and the neutron emissions have been observed for 200 shots without changing the gas in between the shots. The maximum yield of this device is 7.8 x 10{sup 4} neutrons/pulse. Beyond 200 shots the yield is below the threshold (1050 neutrons/pulse) of our {sup 3}He detector. The neutron energy is evaluated using time of flight technique and the value is (2.49 {+-} 0.27) MeV. The measured neutron pulse width is (24 {+-} 5) ns. Multishot and long duration operations envisage the potentiality of such portable device for repetitive mode of operation.
Niranjan, Ram; Rout, R. K.; Srivastava, Rohit; Rawool, A. M.; Kaushik, T. C.; Gupta, Satish C. [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Mishra, Prabhat [Materials Processing Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)
ORNL Neutron Sciences Annual Report for 2007
This is the first annual report of the Oak Ridge National Laboratory Neutron Sciences Directorate for calendar year 2007. It describes the neutron science facilities, current developments, and future plans; highlights of the year's activities and scientific research; and information on the user program. It also contains information about education and outreach activities and about the organization and staff. The Neutron Sciences Directorate is responsible for operation of the High Flux Isotope Reactor and the Spallation Neutron Source. The main highlights of 2007 were highly successful operation and instrument commissioning at both facilities. At HFIR, the year began with the reactor in shutdown mode and work on the new cold source progressing as planned. The restart on May 16, with the cold source operating, was a significant achievement. Furthermore, measurements of the cold source showed that the performance exceeded expectations, making it one of the world's most brilliant sources of cold neutrons. HFIR finished the year having completed five run cycles and 5,880 MWd of operation. At SNS, the year began with 20 kW of beam power on target; and thanks to a highly motivated staff, we reached a record-breaking power level of 183 kW by the end of the year. Integrated beam power delivered to the target was 160 MWh. Although this is a substantial accomplishment, the next year will bring the challenge of increasing the integrated beam power delivered to 887 MWh as we chart our path toward 5,350 MWh by 2011.
Anderson, Ian S [ORNL; Horak, Charlie M [ORNL; Counce, Deborah Melinda [ORNL; Ekkebus, Allen E [ORNL
Neutron imaging with coded sources: new challenges and the implementation of a simultaneous iterative reconstruction technique
The limitations in neutron flux and resolution (L/D) of current neutron imaging systems can be addressed with a Coded Source Imaging system with magnification (xCSI). More precisely, the multiple sources in an xCSI system can exceed the flux of a single pinhole system for several orders of magnitude, while maintaining a higher L/D with the small sources. Moreover, designing for an xCSI system reduces noise from neutron scattering, because the object is placed away from the detector to achieve magnification. However, xCSI systems are adversely affected by correlated noise such as non-uniform illumination of the neutron source, incorrect sampling of the coded radiograph, misalignment of the coded masks, mask transparency, and the imperfection of the system Point Spread Function (PSF). We argue that a model-based reconstruction algorithm can overcome these problems and describe the implementation of a Simultaneous Iterative Reconstruction Technique algorithm for coded sources. Design pitfalls that preclude a satisfactory reconstruction are documented.
Santos-Villalobos, Hector J [ORNL; Bingham, Philip R [ORNL; Gregor, Jens [University of Tennessee, Knoxville (UTK)
Energy spectra of the pneumatically positioned neutron sources at LLNL's Hazards control standards and calibration facility
The Hazards Control Department of Lawrence Livermore National Laboratory maintains a Standards and Calibration Laboratory that includes three neutron sources (two /sup 252/Cf and one /sup 238/PuBe that can be positioned pneumatically for irradiations. Ten moderators exist to modify the neutron energy spectra produced by these sources. The thicknesses and materials of these moderators are: 25-cm water; 5-, 10-, 15-, and 25-cm heavy water; 20-cm aluminum; and 2-, 5-, 10-, and 15-cm polyethylene. We used a multisphere spectrometer to measure the neutron spectra at 2 m from both the PuBe source and the smaller Cf source, with the sources bare, and in all of the moderators. These data were reduced in 25 energy groups ranging from 0.25 eV to 16 MeV. Except for the 15-m polyethylene moderator, we also made measurements using a liquid-scintillator fast-neutron spectrometer. These data were reduced in 0.1-MeV increments from 0.5 to 12.5 MeV. Spectra from the measurements and from independent calculations are presented in tabular and graphic form. Dosimetric values, calculated from both the measured and calculated spectra, are also presented.
Thorngate, J.H.
A dual neutron/gamma source for the Fissmat Inspection for Nuclear Detection (FIND) system.
Shielded special nuclear material (SNM) is very difficult to detect and new technologies are needed to clear alarms and verify the presence of SNM. High-energy photons and neutrons can be used to actively interrogate for heavily shielded SNM, such as highly enriched uranium (HEU), since neutrons can penetrate gamma-ray shielding and gamma-rays can penetrate neutron shielding. Both source particles then induce unique detectable signals from fission. In this LDRD, we explored a new type of interrogation source that uses low-energy proton- or deuteron-induced nuclear reactions to generate high fluxes of mono-energetic gammas or neutrons. Accelerator-based experiments, computational studies, and prototype source tests were performed to obtain a better understanding of (1) the flux requirements, (2) fission-induced signals, background, and interferences, and (3) operational performance of the source. The results of this research led to the development and testing of an axial-type gamma tube source and the design/construction of a high power coaxial-type gamma generator based on the {sup 11}B(p,{gamma}){sup 12}C nuclear reaction.
Doyle, Barney Lee (Sandia National Laboratories, Albuquerque, NM); King, Michael; Rossi, Paolo (Sandia National Laboratories, Albuquerque, NM); McDaniel, Floyd Del (Sandia National Laboratories, Albuquerque, NM); Morse, Daniel Henry; Antolak, Arlyn J.; Provencio, Paula Polyak (Sandia National Laboratories, Albuquerque, NM); Raber, Thomas N.
Capabilities of the ARCS Instrument - ORNL Neutron Sciences
Capabilities of the ARCS Instrument Capabilities of the ARCS Instrument ARCS Overview The wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source (SNS) is optimized to provide a high neutron flux at the sample position with a large solid angle of detector coverage. The instrument incorporates modern neutron instrumentation, such as an elliptically focused neutron guide, high speed magnetic bearing choppers, and a massive array of 3He linear position sensitive detectors. Novel features of the spectrometer include the use of a large gate valve between the sample and detector vacuum chambers and the placement of the detectors within the vacuum, both of which provide a window-free final flight path to minimize background scattering while allowing rapid changing of the sample and
SCIENCE HIGHLIGHTS 2008 ANNUAL REPORT ORNL NEUTRON SCIENCES neutrons.ornl.gov
of the campus, High Flux Isotope Reactor (HFIR), Conference Center and short walk to the Spallation Neutron nearby Reservations can be made 24/7 by calling 865-576-8101 Map of ORNL Campus #12;Maps of SNS, HFIR
Can Handheld Plastic Detectors Do Both Gamma and Neutron Isotopic Identification with Directional Source Location?
This paper demonstrates, through MCNPX simulations, that a compact hexagonal array of detectors can be utilized to do both gamma isotopic identification (ID) along with neutron identification while simultaneously finding the direction of the source relative to the detector array. The detector array itself is composed of seven borated polyvinyl toluene (PVT) hexagonal light pipes approximately 4 inches long and with a 1.25 inch face-to-face thickness assembled in a tight configuration. The gamma ID capability is realized through judicious windowing algorithms as is the neutron spectral unfolding. By having multiple detectors in different relative positions, directional determination of the source can be realized. By further adding multiplicity counters to the neutron counts, fission events can be measured.
Robert Hayes
An Ultracold Neutron Source for TRIUMF 4th Draft #
location is the availability of hot cells with which to handle safely parts of the UCN source. Additionally handling hot cells for servicing. . existing 50 T crane is available in the area for shielding blocks, target cooling, and remote handling are based predominantly on our experience from the LANL SD 2 UCN
School on Neutron and X-ray Scattering Oak Ridge 10-24 August 2013 John M. Carpenter ANL, ORNLSNS 18 August 2013 2 Neutron Detection How does one detect a neutron? - It is...
This paper describes the usage of the XAL online model for transverse and longitudinal tuning of the SNS linac. Most of the SNS control room physics applications are based on the XAL online model, which can be synchronized with an accelerator live state and used to tune the machine. Advantages of a simple and fast single particle model for orbit correction and longitudinal dynamics control in the SNS control room are discussed.
Shishlo, Andrei P [ORNL; Aleksandrov, Alexander V [ORNL
GDT-based neutron source with multiple-mirror end plugs
We present a new linear trap to be built at the Budker Institute. It combines gasdynamictype central cell with sloshing ions for beam fusion and the multiple-mirror end plugs for improved axial confinement. Thus it is designed as an efficient neutron source and a testbed for future development of mirror-based fusion reactors.
Beklemishev, A.; Anikeev, A.; Burdakov, A.; Ivanov, A.; Ivanov, I.; Postupaev, V.; Sinitsky, S. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation)
Stockli, R. Welton, and M. White (SNS-ORNL); J. Power and M.VI. REFERENCES N. Holtkamp, �The SNS Linac and Storage Ring:the FES Team, �Status of the SNS Front-End Sys- tems, Paper
Industry and Neutron Science Industry and Neutron Science Industry and Neutron Science: Working To Make a Match "In fundamental research, we want to know everything. Industry wants to know enough to answer a question." Research Contact: Mike Crawford September 2011, Written by Deborah Counce Mike Crawford and Souleymane Diallo Mike Crawford of Dupont (right) and Souleymane Diallo, instrument scientist for the Backscattering Spectrometer at SNS, prepare a material sample for an experiment on the instrument. Industrial users are starting to eye the potential of neutron science for solving problems that can't be solved in any other way. At the same time, the SNS and HFIR neutron science facilities at ORNL are exploring ways to woo such users and to make a match of it, to the benefit of both.
SEQUOIA: the Fine-Resolution Fermi Chopper Spectrometer at SNS...
of novel systems and materials that are currently unknown and complements the other main SNS chopper spectrometer, ARCS. In general, SEQUOIA is the instrument of choice for...
High-flux neutron source based on a liquid-lithium target
A prototype compact Liquid Lithium Target (LiLiT), able to constitute an accelerator-based intense neutron source, was built. The neutron source is intended for nuclear astrophysical research, boron neutron capture therapy (BNCT) in hospitals and material studies for fusion reactors. The LiLiT setup is presently being commissioned at Soreq Nuclear research Center (SNRC). The lithium target will produce neutrons through the {sup 7}Li(p,n){sup 7}Be reaction and it will overcome the major problem of removing the thermal power generated by a high-intensity proton beam, necessary for intense neutron flux for the above applications. The liquid-lithium loop of LiLiT is designed to generate a stable lithium jet at high velocity on a concave supporting wall with free surface toward the incident proton beam (up to 10 kW). During off-line tests, liquid lithium was flown through the loop and generated a stable jet at velocity higher than 5 m/s on the concave supporting wall. The target is now under extensive test program using a high-power electron-gun. Up to 2 kW electron beam was applied on the lithium flow at velocity of 4 m/s without any flow instabilities or excessive evaporation. High-intensity proton beam irradiation will take place at SARAF (Soreq Applied Research Accelerator Facility) superconducting linear accelerator currently in commissioning at SNRC.
Halfon, S. [Soreq NRC, Yavne, 81800 (Israel) and Racah Institute of Physics, Hebrew University, Jerusalem, 91904 (Israel); Feinberg, G. [Soreq NRC, Yavne, 81800 (Israel) and Racah Institute of Physics, Hebrew University, Jerusalem, 91904 (Israel); Paul, M. [Racah Institute of Physics, Hebrew University, Jerusalem, 91904 (Israel); Arenshtam, A.; Berkovits, D.; Kijel, D.; Nagler, A.; Eliyahu, I.; Silverman, I. [Soreq NRC, Yavne, 81800 (Israel)
BES Science Network Requirements
Spallation Neutron Source (SNS) and the High Flux Isotopea centralized data archive at SNS. A single measurement isof the two facilities SNS and HFIR, SNS has the ability to
Dart, Eli
Subcritical measurements using the /sup 252/Cf source-driven neutron noise analysis method
This paper describes recent measurements of the subcritical neutron multiplication factor using the /sup 252/Cf source-driven neutron noise analysis method. This work was supported by a program of collaboration between the United States Department of Energy and the Power Reactor and Nuclear Fuel Development Corporation of Japan related to the development of fast breeder technology. The experiment reported consists of a configuration of two interacting tanks of uranyl nitrate aqueous solution with different uranium concentrations in each tank. The /sup 252/Cf-source-driven neutron noise analysis method obtains the subcriticality from the signals of three detectors: the first, a parallel plate ionization chamber with /sup 252/Cf electroplated on one of its plates that is located in or near the system containing the fissile material, and produces an electrical pulse for every spontaneous fission that occurs and thereby serves as a timed source of fission neutrons; and the second and third detectors that are placed in or near the system containing fissile material and serve to detect particles from the fission chain multiplication process. 9 refs.
Mihalczo, J.T.; Blakeman, E.D.; Ragan, G.E.; Kryter, R.C.
2011 U.S. National School on Neutron and X-ray Scattering
The 13th annual U.S. National School on Neutron and X-ray Scattering was held June 11 to 25, 2011, at both Oak Ridge and Argonne National Laboratories. This school brought together 65 early career graduate students from 56 different universities in the US and provided them with a broad introduction to the techniques available at the major large-scale neutron and synchrotron x-ray facilities. This school is focused primarily on techniques relevant to the physical sciences, but also touches on cross-disciplinary bio-related scattering measurements. During the school, students received lectures by over 30 researchers from academia, industry, and national laboratories and participated in a number of short demonstration experiments at Argonne's Advanced Photon Source (APS) and Oak Ridge's Spallation neutron Source (SNS) and High Flux Isotope Reactor (HFIR) facilities to get hands-on experience in using neutron and synchrotron sources. The first week of this year's school was held at Oak Ridge National Lab, where Lab director Thom Mason welcomed the students and provided a shitorical perspective of the neutron and x-ray facilities both at Oak Ridge and Argonne. The first few days of the school were dedicated to lectures laying out the basics of scattering theory and the differences and complementarity between the neutron and x-ray probes given by Sunil Sinha. Jack Carpenter provided an introduction into how neutrons are generated and detected. After this basic introduction, the students received lectures each morning on specific techniques and conducted demonstration experiments each afternoon on one of 15 different instruments at either the SNS or HFIR. Some of the topics covered during this week of the school included inelastic neutron scattering by Bruce Gaulin, x-ray and neutron reflectivity by Chuck Majkrazak, small-angle scattering by Volker Urban, powder diffraction by Ashfia Huq and diffuse scattering by Gene Ice.
Lang, Jonathan [Argonne National Laboratory (ANL); te Vethuis, Suzanne [Argonne National Laboratory (ANL); Ekkebus, Allen E [ORNL; Chakoumakos, Bryan C [ORNL; Budai, John D [ORNL
Scientific Labs | Neutron Science | ORNL
Scientific Labs Scientific Labs SHARE SNS Scientific Labs Meilleur-lab-students-300.jpg Students in the SNS chemistry lab practice pipetting water. A new complex of laboratories is now open at SNS, providing a flexible, mobile environment where users can work efficiently. The labs, on the second floor of the SNS Central Laboratory and Office Building, are built with "green" operations in mind, as well as to optimize the available space for researchers' ever-changing scientific needs. With overhead utilities and mobile furniture, the complex's 13 labs allow staff to easily reconfigure the layout of equipment and quickly change an experiment's setup as needed. "We surveyed more than 900 users on what they needed, and they gave us a wish list," says Chrissi Schnell, the Neutron Scattering Science Division
Phase 1 environmental report for the Advanced Neutron Source at Oak Ridge National Laboratory
The US Department of Energy (DOE) has proposed the construction and operation of the Advanced Neutron Source (ANS), a 330-MW(f) reactor, at Oak Ridge National Laboratory (ORNL) to support neutron scattering and nuclear physics experiments. ANS would provide a steady-state source of neutrons that are thermalized to produce sources of hot, cold, and very coal neutrons. The use of these neutrons in ANS experiment facilities would be an essential component of national research efforts in basic materials science. Additionally, ANS capabilities would include production of transplutonium isotopes, irradiation of potential fusion and fission reactor materials, activation analysis, and production of medical and industrial isotopes such as {sup 252}Cf. Although ANS would not require licensing by the US Nuclear Regulatory Commission (NRC), DOE regards the design, construction, and operation of ANS as activities that would produce a licensable facility; that is, DOE is following the regulatory guidelines that NRC would apply if NRC were licensing the facility. Those guidelines include instructions for the preparation of an environmental report (ER), a compilation of available data and preliminary analyses regarding the environmental impacts of nuclear facility construction and operation. The ER, described and outlined in NRC Regulatory Guide 4.2, serves as a background document to facilitate the preparation of environmental impact statements (EISs). Using Regulatory Guide 4.2 as a model, this ANS ER provides analyses and information specific to the ANS site and area that can be adopted (and modified, if necessary) for the ANS EIS. The ER is being prepared in two phases. Phase 1 ER includes many of the data and analyses needed to prepare the EIS but does not include data or analyses of alternate sites or alternate technologies. Phase 2 ER will include the additional data and analyses stipulated by Regulatory Guide 4.2.
Blasing, T.J.; Brown, R.A.; Cada, G.F.; Easterly, C.; Feldman, D.L.; Hagan, C.W.; Harrington, R.M.; Johnson, R.O.; Ketelle, R.H.; Kroodsma, R.L.; McCold, L.N.; Reich, W.J.; Scofield, P.A.; Socolof, M.L.; Taleyarkhan, R.P.; Van Dyke, J.W.
Science-Driven Network Requirements for ESnet
of the science done at SNS, which runs 24 hr/day. � 2 Gbits/Spallation Neutron Source (SNS) from Basic Energy Sciences;Spallation Neutron Source (SNS) is a new facility at the Oak
R&D for a Soft X-Ray Free Electron Laser Facility
S.H. Kim, D. Mangra, ORNL-SNS; D. Barni, C. Pagani, P.for the Spallation Neutron Source (SNS) project,� 50. StuartSpallation Neutron Source (SNS) cavities operate. This may
Staples, John
ORNL Neutron Sciences Instruments
Instruments banner Instruments banner ORNL Neutron Sciences Instruments SNS and HFIR provide researchers with two complementary world-class suites of neutron scattering instruments and beam lines. All the instruments are supported by a variety of sample environments and data analysis and visualization capabilities. Before submitting a proposal for a specific instrument, please contact the appropriate instrument scientist to make sure your research is feasible for that instrument. Instruments Currently Available to Users SNS Beam Line Instrument Name HFIR Beam Line Instrument Name 1B NOMAD Nanoscale-Ordered Materials Diffractometer CG-1 Development Beam Line 2 BASIS Backscattering Spectrometer CG-1D IMAGING Neutron Imaging Prototype Facility 3 SNAP Spallation Neutrons and Pressure Diffractometer CG-2 GP-SANS
ICANS-XIV. The fourteenth meeting of the international collaboration on advanced neutron sources.
The meeting began with a reception on Sunday evening. Monday's plenary sessions included status reports on the four operating spallation neutron sources, IPNS, ISIS, KENS, and the Lujan Center; on the INR source under construction at Troitsk; on the IBR-2 pulsed reactor at Dubna; and on proposals for five new installations. We also heard reports on spin-off activities: the ASTE tests (liquid mercury target tests at the AGS accelerator at Brookhaven), the ACoM activities (developments aimed to provide cold moderators suitable for high-power pulsed sources), and the International Workshop on Cold Moderators for Pulsed Neutron Sources, held in September 1997 at Argonne. Jose Alonso and Bob Macek delivered enlightening invited talks overviewing linear accelerators and rings for spallation neutron sources. The rest of the meeting was devoted to targets and moderators and to instrumentation in a normal rotation of ICANS topics. There were altogether 84 oral reports and 23 poster presentations. On Tuesday and on Wednesday morning, we divided into separate series of sessions on Instrumentation and on Targets and Moderators. In the first, we had reports and discussions on instrumentation and techniques, on computer software, on instrument suites, and on new instruments and equipment. In the second series were sessions on liquid target systems, on solid target systems, on neutron production and target physics, on moderator physics and performance, and on target and moderator neutronics. The Tuesday evening meetings went on until 10:00, making for a 14-hour working day. That everyone willingly endured the long hours is a credit to the dedication of the attendees. On Wednesday afternoon, we boarded buses for the 1-hour trip to Argonne, where attendees toured IPNS and the Advanced Photon Source. Returning to Starved Rock, we enjoyed boat rides on the Illinois River and then a barbecue banquet dinner at the Lodge. All day Thursday and Friday morning, the attendees, in small working groups, discussed next-generation powder diffractometers, critical heat flux limitations on solid targets, monte carlo instrument simulation, prospects for high- and low-energy spectroscopy, small angle scattering and reflectometry, and the roles of solid and liquid targets in high-power pulsed spallation sources. Representatives of the laboratories participating in ICANS met Thursday evening to discuss the outcome of ICANS XIV and to decide whether, where, and when the next meeting would take place. They agreed to meet again in about 2 years in Japan. After the lunch break on Friday, the working group chairs presented the findings of their groups to the participants in a final plenary session, and the meeting adjourned with good feelings of accomplishment.
Carpenter, J. M., ed.; Tobin, C. A., ed.
Performance of the solid deuterium ultra-cold neutron source at the pulsed reactor TRIGA Mainz
The performance of the solid deuterium ultra-cold neutron source at the pulsed reactor TRIGA Mainz with a maximum peak energy of 10 MJ is described. The solid deuterium converter with a volume of V=160 cm3 (8 mol), which is exposed to a thermal neutron fluence of 4.5x10^13 n/cm2, delivers up to 550 000 UCN per pulse outside of the biological shield at the experimental area. UCN densities of ~ 10/cm3 are obtained in stainless steel bottles of V ~ 10 L resulting in a storage efficiency of ~20%. The measured UCN yields compare well with the predictions from a Monte Carlo simulation developed to model the source and to optimize its performance for the upcoming upgrade of the TRIGA Mainz into a user facility for UCN physics.
J. Karch; Yu. Sobolev; M. Beck; K. Eberhardt; G. Hampel; W. Heil; R. Kieser; T. Reich; N. Trautmann; M. Ziegner
A Permanent-Magnet Microwave Ion Source for a Compact High-Yield Neutron Generator
We present recent work on the development of a microwave ion source that will be used in a high-yield compact neutron generator for active interrogation applications. The sealed tube generator will be capable of producing high neutron yields, 5x1011 n/s for D-T and ~;;1x1010 n/s for D-D reactions, while remaining transportable. We constructed a microwave ion source (2.45 GHz) with permanent magnets to provide the magnetic field strength of 87.5 mT necessary for satisfying the electron cyclotron resonance (ECR) condition. Microwave ion sources can produce high extracted beam currents at the low gas pressures required for sealed tube operation and at lower power levels than previously used RF-driven ion sources. A 100 mA deuterium/tritium beam will be extracted through a large slit (60x6 mm2) to spread the beam power over a larger target area. This paper describes the design of the permanent-magnet microwave ion source and discusses the impact of the magnetic field design on the source performance. The required equivalent proton beam current density of 40 mA/cm2 was extracted at a moderate microwave power of 400 W with an optimized magnetic field.
Waldmann, Ole; Ludewigt, Bernhard
Black hole neutron star coalescence as a source of gamma-ray bursts
We present the results of hydrodynamic (SPH) simulations showing the coalescence of a black hole with a neutron star to be a promising theoretical source of short duration gamma-ray bursts. The favorable features of the process include rapid onset, millisecond variability, a duration much longer than the dynamical timescale, and a range of outcomes sufficient to allow variety in the properties of individual gamma-ray bursts. Interestingly, the process of coalescence differs rather markedly from past predictions.
W. H. Lee; W. Kluzniak
The Accelerator Production of Tritium neutron source consists of clad tungsten targets, which are concentric cylinders with a center rod. These targets are arranged in a matrix of tubes, producing a large number of parallel coolant paths. The coolant flow required to meet thermal-hydraulic design criteria varies with location. This paper describes the work performed to ensure an adequate coolant flow for each target for normal operation and residual heat-removal conditions.
Neutron Energy Spectrum of a Po-Be (alpha,n) Source
The newtron energy spectrum of a Po-Be (alpha, n) source was measured as part of an intercomparison of newtron energy spectral measurements sponsored by Oak Ridge National Laboratory. Intensity maxima for neutron energies > 1 MeV were seen at or near 1.4, 2.1, 3.1, 5.0, 6.7, 7.7 and 9.7 MeV.
Anderson, M. E.
Neutron and Nano User Meeting | ornl.gov
Neutrons and Nano User Meeting Aug 12 2013 08-12-2013 08:00 AM - 08-15-2013 05:00 PM The Executive Committees of the SNS-HFIR User Group (SHUG) and the Center for Nanophase...
The Oak Ridge Spallation Neutron Source accumulator ring presently operates at a beam power of about 1 MW with a beam energy of about 910 MeV. A power upgrade is planned to increase the beam energy to 1.3 GeV. For the accumulator ring this mostly involves modifications to the injection and extraction sections. A variety of modifications to the existing injection section were necessary to achieve 1 MW, and the tools developed and the lessons learned from this work are now being applied to the design of the new injection section. This paper will discuss the tools and the lessons learned, and also present the design and status of the upgrades to the accumulator ring.
Plum, Michael A [ORNL; Gorlov, Timofey V [ORNL; Holmes, Jeffrey A [ORNL; Hunter, W Ted [ORNL; Roseberry, Jr., R Tom [ORNL; Wang, Jian-Guang [ORNL
A Survey of Students from the National School on Neutron and X-ray Scattering: Communication Habits and Preferences
Oak Ridge National Laboratory (ORNL) offers the scientific community unique access to two types of world-class neutron sources at a single site - the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR). The 85-MW HFIR provides one of the highest steady-state neutron fluxes of any research reactor in the world. And the SNS is one of the world's most intense pulse neutron beams. Management of these resources is the responsibility of the Neutron Sciences Directorate (NScD). NScD started conducting the National School on Neutron and X-ray Scattering (NXS) in conjunction with the Advanced Photon Source (APS) at Argonne National Laboratory in 2007. This survey was conducted to determine the most effective ways to reach students with information about what SNS and HFIR offer the scientific community, including content and communication vehicles. The emphasis is on gaining insights into compelling messages and the most effective channels, e.g., Web sites and social media, for communicating with students about neutron science The survey was conducted in two phases using a classic qualitative investigation to confirm language and content followed by a survey designed to quantify issues, assumptions, and working hypotheses. Phase I consisted of a focus group in late June 2010 with students attending NXS. The primary intent of the group was to inform development of an online survey. Phase two consisted of an online survey that was developed and pre-tested in July 2010 and launched on August 9, 2010 and remained in the field until September 9, 2010. The survey achieved an overall response rate of 48% for a total of 157 completions. The objective of this study is to determine the most effective ways to reach students with information about what SNS and HFIR offer the scientific community, including content and communication vehicles. The emphasis is on gaining insights into compelling messages and the most effective channels, e.g., Web sites, social media, for communicating with students about neutron science.
Bryant, Rebecca [Bryant Research, LLC
Containment performance analyses for the Advanced Neutron Source Reactor at the Oak Ridge National Laboratory
This paper discusses salient aspects of methodology, assumptions, and modeling of various features related to estimation of source terms from two conservatively scoped severe accident scenarios in the Advanced Neutron Source (ANS) reactor at the Oak Ridge National Laboratory. Various containment configurations are considered for steaming-pool-type accidents and an accident involving molten core-concrete interaction. Several design features (such as rupture disks) are examined to study containment response during postulated severe accidents. Also, thermal-hydraulic response of the containment and radionuclide transport and retention in the containment are studied. The results are described as transient variations of source terms for each scenario, which are to be used for studying off-site radiological consequences and health effects for these postulated severe accidents. Also highlighted will be a comparison of source terms estimated by two different versions of the MELCOR code.
Kim, S.H.; Taleyarkhan, R.P.; Georgevich, V.
(International Panel on 14 MeV Intense Neutron Source Based on Accelerators for Fusion Materials Study)
Both travelers were members of a nine-person US delegation that participated in an international workshop on accelerator-based 14 MeV neutron sources for fusion materials research hosted by the University of Tokyo. Presentations made at the workshop reviewed the technology developed by the FMIT Project, advances in accelerator technology, and proposed concepts for neutron sources. One traveler then participated in the initial meeting of the IEA Working Group on High Energy, High Flux Neutron Sources in which efforts were begun to evaluate and compare proposed neutron sources; the Fourth FFTF/MOTA Experimenters' Workshop which covered planning and coordination of the US-Japan collaboration using the FFTF reactor to irradiate fusion reactor materials; and held discussions with several JAERI personnel on the US-Japan collaboration on fusion reactor materials.
Thoms, K.R.; Wiffen, F.W.
SNS CITY - An exploratory study about the differences between social networking site (SNS) contacts, face-to-face contacts, and contacts both known from SNS's and face-to-face.
??In this thesis the differences between social networking site (SNS) contacts, face-to-face contacts and contacts both known from SNS�s and face-to-face, are of interest. Not� (more)
Dries, T.
Intense Pulsed Neutron Source: Progress report 1991--1996. 15. Anniversary edition -- Volume 1
The 15th Anniversary Edition of the IPNS Progress Report is being published in recognition of the Intense Pulsed Neutron Source`s first 15 years of successful operation as a user facility. To emphasize the importance of this milestone, the authors have made the design and organization of the report significantly different from previous IPNS Progress Reports. This report consists of two volumes. For Volume 1, authors were asked to prepare articles that highlighted recent scientific accomplishments at IPNS, from 1991 to present; to focus on and illustrate the scientific advances achieved through the unique capabilities of neutron studies performed by IPNS users; to report on specific activities or results from an instrument; or to focus on a body of work encompassing different neutron-scattering techniques. Articles were also included on the accelerator system, instrumentation, computing, target, and moderators. A list of published and ``in press` articles in journals, books, and conference proceedings, resulting from work done at IPNS since 1991, was compiled. This list is arranged alphabetically according to first author. Publication references in the articles are listed by last name of first author and year of publication. The IPNS experimental reports received since 1991 are compiled in Volume 2. Experimental reports referenced in the articles are listed by last name of first author, instrument designation, and experiment number.
Marzec, B. [ed.
Intense Pulsed Neutron Source: Progress report 1991--1996. 15. Anniversary edition -- Volume 2
The 15th Anniversary Edition of the IPNS Progress Report is being published in recognition of the Intense Pulsed Neutron Source`s first 15 years of successful operation as a user facility. To emphasize the importance of this milestone, the author shave made the design and organization of the report significantly different from previous IPNS Progress Reports. This report consists of two volumes. For Volume 1, authors were asked to prepare articles that highlighted recent scientific accomplishments at IPNS, from 1991 to present; to focus on and illustrate the scientific advances achieved through the unique capabilities of neutron studies performed by IPNS users; to report on specific activities or results from an instrument; or to focus on a body of work encompassing different neutron-scattering techniques. Articles were also included on the accelerator system, instrumentation, computing, target, and moderators. A list of published and ``in press` articles in journals, books, and conference proceedings, resulting from work done at IPNS since 1991, was compiled. This list is arranged alphabetically according to first author. Publication references in the articles are listed by last name of first author and year of publication. The IPNS experimental reports received since 1991 are compiled in Volume 2. Experimental reports referenced in the articles are listed by last name of first author, instrument designation, and experiment number.
A graphite-moderated pulsed spallation ultra-cold neutron source
Proposals exist and efforts are under way to construct pulsed spallation ultra-cold neutron (UCN) sources at accelerator laboratories around the world. At the Paul Scherrer Institut (PSI), Switzerland, and at the Los Alamos National Laboratory (LANL), U.S.A., it is planned to use solid deuterium (SD_2) for the UCN production from cold neutrons. The philosophies about how the cold neutrons are obtained are quite different, though. The present proposal describes a third approach which applies a temperature optimized graphite moderator in combination with the SD_2 and qualitatively combines advantages of the different schemes. The scheme described here allows to build a powerful UCN source. Assuming a pulsed 2 mA, 590 MeV proton beam with an average current of 10 microA, one obtains UCN densities in excess of 2000 cm^{-3}, UCN fluxes of about 10^6 cm^{-2} s^{-1}, and total numbers of UCN in excess of 2*10^9 every 800 s.
Klaus Kirch
Shielding analysis and design of the KIPT experimental neutron source facility of Ukraine.
Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the conceptual design development of an experimental neutron source facility based on the use of an electron accelerator driven subcritical (ADS) facility [1]. The facility uses the existing electron accelerators of KIPT in Ukraine. The neutron source of the sub-critical assembly is generated from the interaction of 100 KW electron beam with a natural uranium target. The electron beam has a uniform spatial distribution and the electron energy in the range of 100 to 200 MeV, [2]. The main functions of the facility are the production of medical isotopes and the support of the Ukraine nuclear power industry. Reactor physics experiments and material performance characterization will also be carried out. The subcritical assembly is driven by neutrons generated by the electron beam interactions with the target material. A fraction of these neutrons has an energy above 50 MeV generated through the photo nuclear interactions. This neutron fraction is very small and it has an insignificant contribution to the subcritical assembly performance. However, these high energy neutrons are difficult to shield and they can be slowed down only through the inelastic scattering with heavy isotopes. Therefore the shielding design of this facility is more challenging relative to fission reactors. To attenuate these high energy neutrons, heavy metals (tungsten, iron, etc.) should be used. To reduce the construction cost, heavy concrete with 4.8 g/cm{sup 3} density is selected as a shielding material. The iron weight fraction in this concrete is about 0.6. The shape and thickness of the heavy concrete shield are defined to reduce the biological dose equivalent outside the shield to an acceptable level during operation. At the same time, special attention was give to reduce the total shield mass to reduce the construction cost. The shield design is configured to maintain the biological dose equivalent during operation {le} 0.5 mrem/h inside the subcritical hall, which is five times less than the allowable dose for working forty hours per week for 50 weeks per year. This study analyzed and designed the thickness and the shape of the radial and top shields of the neutron source based on the biological dose equivalent requirements inside the subcritical hall during operation. The Monte Carlo code MCNPX is selected because of its capabilities for transporting electrons, photons, and neutrons. Mesh based weight windows variance reduction technique is utilized to estimate the biological dose outside the shield with good statistics. A significant effort dedicated to the accurate prediction of the biological dose equivalent outside the shield boundary as a function of the shield thickness without geometrical approximations or material homogenization. The building wall was designed with ordinary concrete to reduce the biological dose equivalent to the public with a safety factor in the range of 5 to 20.
Zhong, Z.; Gohar, M. Y. A.; Naberezhnev, D.; Duo, J.; Nuclear Engineering Division
Thermal neutron detection system
According to the present invention, a system for measuring a thermal neutron emission from a neutron source, has a reflector/moderator proximate the neutron source that reflects and moderates neutrons from the neutron source. The reflector/moderator further directs thermal neutrons toward an unmoderated thermal neutron detector.
Peurrung, Anthony J. (Richland, WA); Stromswold, David C. (West Richland, WA)
Oak Ridge Reservation site evaluation report for the Advanced Neutron Source
The Advanced Neutron Source (ANS) is a research reactor that is the US Department of Energy (DOE) plans to build for initial service late in this century. The primary purpose of the ANS is to provide a useable neutron flux for scattering experiments 5 to 10 times as a high as that generated by any existing research reactor, secondary purposes include production of a variety of transuranic and other isotopes and irradiation of materials. The ANS is proposed to be located on the DOE Oak Ridge Reservation (ORR) at Oak Ridge, Tennessee, and operated by the Oak Ridge National Laboratory (ORNL). This report documents the evaluation of alternative sites on the ORR and the selection of a site for the ANS.
Sigmon, B.; Heitzman, A.C. Jr.; Morrissey, J. [Science Applications International Corp., Oak Ridge, TN (United States)
Characteristics of a RF-Driven Ion Source for a Neutron Generator Used for Associated Particle Imaging
We present recent work on a prototype compact neutron generator for associated particle imaging (API). API uses alpha particles that are produced simultaneously with neutrons in the deuterium-tritium ({sup 2}D({sup 3}T,n){sup 4}{alpha}) fusion reaction to determine the direction of the neutrons upon exiting the reaction. This method determines the spatial position of each neutron interaction and requires the neutrons to be generated from a small spot in order to achieve high spatial resolution. The ion source for API is designed to produce a focused ion beam with a beam spot diameter of 1-mm or less on the target. We use an axial type neutron generator with a predicted neutron yield of 10{sup 8} n/s for a 50 {mu}A D/T ion beam current accelerated to 80 kV. The generator utilizes an RF planar spiral antenna at 13.56 MHz to create a highly efficient inductively coupled plasma at the ion source. Experimental results show that beams with an atomic ion fraction of over 80% can be obtained while utilizing only 100 watts of RF power in the ion source. A single acceleration gap with a secondary electron suppression electrode is used in the tube. Experimental results from ion source testing, such as the current density, atomic ion fraction, electron temperature, and electron density will be discussed.
Wu Ying; Leung, K.-N. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Department of Nuclear Engineering, University of California-Berkeley, Berkeley, CA 94720 (United States); Hurley, John P. [Special Technologies Laboratory, Santa Barbara, CA 93111 (United States); Ji Qing; Kwan, Joe [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States)
Former User Group Chair Enthusiastic About Relevance of Neutron Scattering Former User Group Chair Enthusiastic About Relevance of Neutron Scattering to Industrial Research Former User Group Chair Mike Crawford Mike Crawford, DuPont Research and Development. The drive is intensifying to encourage research partnerships between Neutron Sciences and private industry. Such partnerships, a long-term strategic goal set by the DOE's Basic Energy Sciences Advisory Committee, will deliver industry and its technological problems to SNS and HFIR, where joint laboratory-industry teams can use the unparalleled resources available here to resolve them. "SNS is a tremendous facility. It has the potential to have a couple of thousand user visits a year and, if they build another target station in the future, you're probably talking about 4000 user visits a year,"
Battery Studies Battery Studies A Wealth of New Battery Research at SNS and HFIR Technical Contacts: Xun-Li Wang, Ashfia Huq, Jung-Hyun Kim October 2010, Written by Carolyn Krause Neutron scattering, capable of looking deep inside the structures of materials used in technologies such as batteries and fuel cells, is a natural tool for research in energy storage and production. Several users of neutron scattering instruments at the SNS and HFIR presented details of their energy-related research to prospective scientific facility users attending the opening session of ORNL's User Week at SNS. Most of the energy-related research reported in the session dealt with batteries for electric and hybrid electric cars. Better batteries are also needed for storing excess electricity generated by wind and solar power so
Analysis of core-concrete interaction event with flooding for the Advanced Neutron Source reactor
This paper discusses salient aspects of the methodology, assumptions, and modeling of various features related to estimation of source terms from an accident involving a molten core-concrete interaction event (with and without flooding) in the Advanced Neutron Source (ANS) reactor at the Oak Ridge National Laboratory. Various containment configurations are considered for this postulated severe accident. Several design features (such as rupture disks) are examined to study containment response during this severe accident. Also, thermal-hydraulic response of the containment and radionuclide transport and retention in the containment are studied. The results are described as transient variations of source terms, which are then used for studying off-site radiological consequences and health effects for the support of the Conceptual Safety Analysis Report for ANS. The results are also to be used to examine the effectiveness of subpile room flooding during this type of severe accident.
Kim, S.H.; Taleyarkhan, R.P.; Georgevich, V.; Navarro-Valenti, S.
Verification of the content, isotopic composition and age of plutonium in Pu-Be neutron sources by gamma-spectrometry
A non-destructive, gamma-spectrometric method for verifying the plutonium content of Pu-Be neutron sources has been developed. It is also shown that the isotopic composition and the age of plutonium (Pu) can be determined in the intensive neutron field of these sources by the ``Multi-Group Analysis'' method. Gamma spectra were taken in the far-field of the sample, which was assumed to be cylindrical. The isotopic composition and the age of Pu were determined using a commercial implementation of the Multi-Group Analysis algorithm. The Pu content of the sources was evaluated from the count rates of the gamma-peaks of 239Pu, relying on the assumption that the gamma-rays are coming to the detector parallel to each other. The determination of the specific neutron yields and the problem of neutron damage to the detector are also discussed.
Nguyen, C T
Cong Tam Nguyen
BASIS: Backscattering Spectrometer at SNS | ORNL Neutron Sciences
Backscattering Spectrometer Backscattering Spectrometer View inside the BAIS tank View inside the BASIS tank. BASIS is a near-backscattering, crystal-analyzer spectrometer that provides very fine energy resolution, as low as 3.0 to 3.5 µeV at the elastic peak (depending on sample size). This requires a long initial guide section of 84 m from moderator to sample in order to achieve the timing resolution necessary for obtaining the desired energy resolution. BASIS provides an excellent dynamic range near the elastic peak of about plus and minus 100 µeV in the standard high-intensity operation regime, which, if needed, could be extended to plus and minus 200 µeV and beyond. The spectrometer is optimized for quasielastic scattering but provides about 0.1% resolution in energy transfers up to ~40 meV; the inelastic excitations need to be
but are not limited to, structural studies of magnetic materials such as high-Tc superconductors, metal-insulator phase transitions, charge and orbital ordering transitions, and...
HYSPEC: the Hybrid Spectrometer at SNS - ORNL Neutron Sciences
Documentation for HYSPEC Documents HYSPEC Status June, 22 2012 HYSPEC Status, May 21, 2012 HYSPEC Status Mar, 29 2012 HYSPEC Status Feb, 28 2012 HYSPEC Status Feb, 5 2013 HYSPC...
2 to 100 meV. Typical applications include spin and lattice dynamics in high-temperature superconductors and related compounds; low-dimensional magnetic model systems; magnetic...
Microsoft Word - atomic_mystery_model_sns_teachers.DOC
of the clay balls with contents for other groups. What does this have to do with SNS? Similar to the way you just used a probe to discover information about an object you...
Observations of Space Charge effects in the Spallation Neutron Source Accumulator Ring
The Spallation Neutron Source accumulator ring was designed to allow independent control of the transverse beam distribution in each plane. However, at high beam intensities, nonlinear space charge forces can strongly influence the final beam distribution and compromise our ability to independently control the transverse distributions. In this study we investigate the evolution of the beam at intensities of up to ~8x10^13 ppp through both simulation and experiment. Specifically, we analyze the evolution of the beam distribution for beams with different transverse aspect ratios and tune splits. We present preliminary results of simulations of our experiments.
Potts III, Robert E [ORNL; Cousineau, Sarah M [ORNL; Holmes, Jeffrey A [ORNL
Modernization of the High Flux Isotope Reactor (HFIR) to Provide a Cold Neutron Source and Experimentation Facility
This paper discusses the installation of a cold neutron source at HFIR with respect to the project as a modernization of the facility. The paper focuses on why the project was required, the scope of the cold source project with specific emphasis on the design, and project management information.
Rothrock, Benjamin G [ORNL; Farrar, Mike B [ORNL
Simultaneous usage of pinhole and penumbral apertures for imaging small scale neutron sources from inertial confinement fusion experiments
Inertial confinement fusion experiments at the National Ignition Facility are designed to understand the basic principles of creating self-sustaining fusion reactions by laser driven compression of deuterium-tritium (DT) filled cryogenic plastic capsules. The neutron imaging diagnostic provides information on the distribution of the central fusion reaction region and the surrounding DT fuel by observing neutron images in two different energy bands for primary (13-17 MeV) and down-scattered (6-12 MeV) neutrons. From this, the final shape and size of the compressed capsule can be estimated and the symmetry of the compression can be inferred. These experiments provide small sources with high yield neutron flux. An aperture design that includes an array of pinholes and penumbral apertures has provided the opportunity to image the same source with two different techniques. This allows for an evaluation of these different aperture designs and reconstruction algorithms.
Guler, N.; Volegov, P.; Danly, C. R.; Grim, G. P.; Merrill, F. E.; Wilde, C. H. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545 (United States)
Transmutation facility for weapons grade plutonium based on a tokamak fusion neutron source
It is suggested that weapons grade plutonium could be processed through a transmutation facility to build up sufficient actinide and fission product inventories to serve as a deterrent to diversion or theft, pending eventual use as nuclear reactor fuel. A transmutation facility consisting of a fusion neutron source surrounded by fuel assemblies containing the weapons grade plutonium in the form of PuO2 pebbles in a lithium slurry was investigated and found to be technically feasible. A design concept/operation scenario was developed for a facility which would be able to transmute the world's estimated inventory of weapons grade plutonium to 11% Pu-240 concentration in about 25 years. The fusion neutron source would be based on tokamak plasma operating conditions and magnet technology being qualified in ongoing R D programs, and the plutonium fuel would be based on existing technology. A new R D program would be required to qualify a refractory metal alloy structural material needed to handle the high heat fluxes. Extensions of existing technologies and acceleration of existing R D programs would seem to be adequate to qualify other technologies required for the facility.
Transmutation facility for weapons-grade plutonium disposition based on a tokamak fusion neutron source
It is suggested that weapons-grade plutonium could be processed through a transmutation facility to build up sufficient actinide and fission product inventories to serve as a deterrent to diversion or theft during subsequent storage, pending eventual use as fuel in commercial nuclear reactors. A transmutation facility consisting of a tokamak fusion neutron source surrounded by fuel assemblies containing the weapons-grade plutonium in the form of PuO{sub 2} pebbles in a lithium slurry is investigated. A design concept/operation scenario is developed for a facility that would be able to transmute the world`s estimated surplus inventory of weapons-grade plutonium to 11% {sup 240}Pu concentration in nearly 25 yr. The fusion neutron source would be based on plasma physics and plasma support technology being qualified in ongoing research and development (R&D) programs, and the plutonium fuel would be based on existing technology. A new R&D program would be required to qualify a refractory metal alloy structural material that would be needed to handle the high heat fluxes; otherwise, extensions of existing technologies and acceleration of existing R&D programs would seem to be adequate to qualify all required technologies. Such a facility might feasibly be deployed in 20 to 30 yr, or sooner with a crash program. 49 refs., 5 figs., 13 tabs.
Stacey, W.M.; Pilger, B.L.; Mowrey, J.A. [Georgia Inst. of Technology, Atlanta, GA (United States)] [and others
Effects of Deformation History on Low-Cycle Fatigue Behavior of a ...
The neutron-diffraction measurements were performed under a continuous ... VULCAN engineering diffractometer at the Spallation Neutron Source (SNS), Oak
Performance of a 14-MeV neutron generator as an in situ calibration source for TFTR
TFTR will soon enter its D-T phase with the introduction of tritium. This will result in the production of neutrons having 14-MeV energy which is significantly greater than the 2.5-MeV neutrons encountered during D-D operation. In preparation for the D-T phase, a calibration of the four neutron detection systems was performed using a 14-MeV neutron generator producing 10{sup 8} n/sec. To account for the spatial extent of the toroidally shaped plasma and for neutrons scattered from surrounding structures, detector responses were determined with the source positioned at many locations inside the vacuum vessel. Before the generator could be used as a calibration source, a characterization of its total yield and angular emission properties was obtained. The total yield was determined by aluminum activation methods to within {plus_minus}6%, while the angular emission was found to be anisotropic in the forward and reverse cones along the generator axis. After the characterization was performed, the generator was mounted on a moveable track inside the vacuum vessel, where it could be remotely moved across the view of each detector. This paper presents details of the methods and results of the source characterization, together with initial results of the in-vessel D-T neutron calibration.
Roquemore, A.L.; Jassby, D.L.; Johnson, L.C.; Strachan, J.D. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Barnes, C.W. [Los Alamos National Lab., NM (United States)
Published Research 2008 | ORNL Neutron Sciences
8 8 Most publications are in Adobe Portable Document Format. Download Adobe Reader. For more information about any of these publications, please contact the Neutrons Sciences Communications Office. Primary Author Index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A Abernathy D. L., "ARCS: a wide Angular-Range Chopper Spectrometer at the SNS", Notiziario Neutroni e Luce di Sincrotrone 13, 4-7 . Ambaye H., Goyette R., Parizzi A., Klose F., "SNS magnetism reflectometer", Neutron News 19, 11-13. Anderson I. S., Horak C. M., Counce D. M., Ekkebus A. E., "ORNL Neutron Sciences Annual Report for 2007", ORNL/TM-2009/111. Ankner J. F., Tao X., Halbert C. E., Browning J. F., Kilbey II S. M., Swader O. A., admun M. S., Kharlampieva E., Sukhishvili S. A., "The SNS
Plans for an Integrated Front-End Test Stand at the Spallation Neutron Source
A spare Radio-Frequency Quadrupole (RFQ) is presently being fabricated by industry with delivery to Oak Ridge National Laboratory planned in late 2012. The establishment of a test stand at the Spallation Neutron Source site is underway so that complete acceptance testing can be performed during the winter of 2012-2013. This activity is the first step in the establishment of an integrated front-end test stand that will include an ion source, low-energy beam transport (LEBT), RFQ, medium-energy beam transport, diagnostics, and a beam dump. The test stand will be capable of delivering an H- ion beam of up to 50 mA with a pulse length of 1 ms and a repetition rate of 60 Hz or a proton beam of up to 50 mA, 100us, 1Hz. The test stand will enable the following activities: complete ion source characterization; development of a magnetic LEBT chopper; development of a two-source layout; development of beam diagnostics; and study of beam dynamics of high intensity beam.
Champion, Mark S [ORNL; Aleksandrov, Alexander V [ORNL; Crofford, Mark T [ORNL; Heidenreich, Dale A [ORNL; Kang, Yoon W [ORNL; Moss, John [ORNL; Roseberry, Jr., R Tom [ORNL; Schubert, James Phillip [ORNL
Final Report US-Japan IEC Workshop on Small Plasma and Accelerator Neutron Sources
Abstract The history of IEC development will be briefly described, and some speculation about future directions will be offered. The origin of IEC is due to the brilliance of Phil Farnsworth, inventor of electronic TV in the US. Early experiments were pioneered in the late 1960s by Robert Hirsch who later became head of the DOE fusion program. At that time studies of IEC physics quickly followed at the University of Illinois and at Penn State University. However, despite many successes in this early work, IEC research died as DOE funding stopped in the mid 1980s. In the early 90�s, R. W. Bussard of EMC revived work with a new major project based on a magnetic assisted IEC. While doing supportive studies for that project, G. Miley proposed a grided �STAR mode� IEC as a neutron source for NAA. This concept was later used commercially by Daimler- Benz in Germany to analysis impurities in incoming ores. This represented a first practical application of the IEC. During this period other research groups at LANL, U of Wisconsin and Kyoto University entered IEC research with innovative new concepts and approaches to IEC physics and applications. Much of this work is documented in the present and in past US-Japan Workshops. At present we stand on the threshold of a new area of IEC applications as neutron source, for isotope production, and as a plasma source. These applications provide a way to continue IEC understanding and technology development with the ultimate goal being a fusion power plant. Indeed, a distinguishing feature of the IEC vs. other fusion confinement approaches is the unique opportunity for �spin off� applications along the way to a power producing plant.
Miley, George, H.
Construction of Thermal Neutron Calibration Fields Using a Graphite Pile and Americium-Beryllium Neutron Sources at KAERI
B. H. Kim; S. M. Jun; J. S. Kim; K. S. Lim; J. L. Kim
A New Low-Energy Neutron Spectrometer Based on Position-Sensitive Proportional Counter for Accelerator-Based Neutron Source
Neutron Measurements / Special Issue on the 11th International Conference on Radiation Shielding and the 15th Topical Meeting of the Radiation Protection and Shielding Division (Part 2) / Radiation Measurements and Instrumentation
I. Murata; H. Miyamaru; I. Kato; S. Yoshida; Y. Mori
Electrostatic LEBTs for High-Intensity Linac-Injectors
R. Yourd, �Progress with the SNS Front End Sys- tems,� Proc.Results Obtained with the SNS H - Ion Source and LEBT atthe Spallation Neutron Source (SNS) front end, the presented
Keller, R.; Kahto, S.K.
--No Title--
Media Relations Communications 865.576.1946 Contract Awarded for SNS Land Improvements OAK RIDGE, Tenn., Dec. 18, 2002 - The Spallation Neutron Source (SNS) project at Oak Ridge...
Advanced Neutron Source enrichment study -- Volume 1: Main report. Final report, Revision 12/94
A study has been performed of the impact on performance of using low enriched uranium (20% {sup 235}U) or medium enriched uranium (35% {sup 235}U) as an alternative fuel for the Advanced Neutron Source, which is currently designed to use uranium enriched to 93% {sup 235}U. Higher fuel densities and larger volume cores were evaluated at the lower enrichments in terms of impact on neutron flux, safety, safeguards, technical feasibility, and cost. The feasibility of fabricating uranium silicide fuel at increasing material density was specifically addressed by a panel of international experts on research reactor fuels. The most viable alternative designs for the reactor at lower enrichments were identified and discussed. Several sensitivity analyses were performed to gain an understanding of the performance of the reactor at parametric values of power, fuel density, core volume, and enrichment that were interpolations between the boundary values imposed on the study or extrapolations from known technology. Volume 2 of this report contains 26 appendices containing results, meeting minutes, and fuel panel presentations.
Bari, R.A.; Ludewig, H.; Weeks, J. [Brookhaven National Lab., Upton, NY (United States). Dept. of Advanced Technology
Advanced neutron source project information management. A model for the future
The Advanced Neutron Source (ANS) is a proposed new research facility that will provide steady-state beams of neutrons for experiments by more than 1000 researchers per year in the fields of materials science and engineering, biology, chemistry, materials analysis, and nuclear science. The facility will also include irradiation capabilities to produce radioisotopes for medical applications, research, industry, and materials testing. This paper discusses the architecture and data flow used by the project, some quantitative examinations of potential cost savings and return on investment and software applications used to generate and manage data across IBM-compatible personal computers, Macintosh, and Unix-based workstations. Personnel management aspects addressed include providing paper copy to users only when needed for adequate technical review, using graded approaches to providing support for numerous user-needed software applications, and implementing a phased approach to compliance with computer-aided acquisition and logistic support (CALS) standards that allows sufficient user flexibility for performing technical tasks while providing needed data sharing and integration.
King-Jones, K.; Cleaves, J.
Advanced Neutron Source project information management: A model for the future
The Advanced Neutron Source (ANS) is a proposed new research facility that will provide steady-state beams of neutrons for experiments by more than 1,000 researchers per year in the fields of materials science and engineering, biology, chemistry, materials analysis, and nuclear science. The facility will also include irradiation capabilities to produce radioisotopes for medical applications, research, industry, and materials testing. This paper discusses the architecture and data flow used by the project, some quantitative examinations of potential cost savings and return on investment, and software applications used to generate and manage data across IBM-compatible personal computers, Macintosh, and Unix-based workstations. Personnel management aspects addressed include providing paper copy to users only when needed for adequate technical review, using graded approaches to providing support for numerous user-needed software applications, and implementing a phased approach to compliance with computer-aided acquisition and logistic support (CALS) standards that allows sufficient user flexibility for performing technical tasks while providing needed data sharing and integration.
Engineering design issues of a low aspect ratio tokamak volumetric neutron source
Engineering design issues of a volumetric neutron source (VNS) based on a steady state low aspect ratio DT tokamak are presented. At the present the major radius is 0.8 m, the minor radius 0.6 m for an aspect ratio of 1.33, the plasma current is 10.1 MA, the toroidal field at the major radius is 1.8 T, the fusion power is 39 MW giving an average neutron wall loading of 1.0 MW/m(2) on the outboard side with an available testing area of 10 m(2). Two neutral beams delivering more than 20 MW are used to drive the steady state fusion plasma. A single turn unshielded water cooled dispersion strengthened (DS) Cu centerpost is used in conjunction with a conducting Cu bell jar which acts as a vacuum boundary and the return legs for the toroidal field (TF) coils. The centerpost is 9 m long, carries 7.2 MA and is specially shaped to minimize ohmic heating, which is calculated using temperature dependent DS Cu properties and increases in resistivity due to nuclear transmutations are accounted for. A naturally diverted plasma scrapeoff layer dominated by pressure-driven instabilities is assumed giving a peak heat flux of 5.2 MW/m(2) on the diverter plates. Fabrication approaches for the centerpost and its replacement time lines have been estimated to be feasible and reasonable.
Record of Decision for the Construction and Operation of the Spallation Neutron Source
140 140 Federal Register / Vol. 64, No. 125 / Wednesday, June 30, 1999 / Notices or minimize environmental harm that may result from implementing the Redevelopment Plan. Accordingly, Navy will dispose of the surplus Federal property at Naval Air Station Barbers Point in a manner that is consistent with the State of Hawaii's Redevelopment Plan for the property. Dated: June 17, 1999. William J. Cassidy, Jr., Deputy Assistant Secretary of the Navy (Conversion And Redevelopment). Dated: June 25, 1999. Ralph W. Corey, CDR, JAGC, USN, Alternate Federal Register Liaison Officer. [FR Doc. 99-16691 Filed 6-29-99; 8:45 am] BILLING CODE 3810-FF-M DEPARTMENT OF ENERGY Record of Decision for the Construction and Operation of the Spallation Neutron Source AGENCY: Department of Energy. ACTION: Record of decision.
The Status of Research Regarding Magnetic Mirrors as a Fusion Neutron Source or Power Plant
Experimental results, theory and innovative ideas now point with increased confidence to the possibility of a Gas Dynamic Trap (GDT) neutron source which would be on the path to an attractively simple Axisymmetric Tandem Mirror (ATM) power plant. Although magnetic mirror research was terminated in the US 20 years ago, experiments continued in Japan (Gamma 10) and Russia (GDT), with a very small US effort. This research has now yielded data, increased understanding, and generated ideas resulting in the new concepts described here. Early mirror research was carried out with circular axisymmetric magnets. These plasmas were MHD unstable due to the unfavorable magnetic curvature near the mid-plane. Then the minimum-B concept emerged in which the field line curvature was everywhere favorable and the plasma was situated in a MHD stable magnetic well (70% average beta in 2XII-B). The Ioffe-bar or baseball-coil became the standard for over 40 years. In the 1980's, driven by success with minimum-B stabilization and the control of ion cyclotron instabilities in PR6 and 2XII-B, mirrors were viewed as a potentially attractive concept with near-term advantages as a lower Q neutron source for applications such as a hybrid fission fuel factory or toxic waste burner. However there are down sides to the minimum-B geometry: coil construction is complex; restraining magnetic forces limit field strength and mirror ratios. Furthermore, the magnetic field lines have geodesic curvature which introduces resonant and neoclassical radial transport as observed in early tandem mirror experiments. So what now leads us to think that simple axisymmetric mirror plasmas can be stable? The Russian GDT experiment achieves on-axis 60% beta by peaking of the kinetic plasma pressure near the mirror throat (where the curvature is favorable) to counter-balance the average unfavorable mid-plane curvature. Then a modest augmentation of plasma pressure in the expander results in stability. The GDT experiments have confirmed the physics of effluent plasma stabilization predicted by theory. The plasma had a mean ion energy of 10 keV and a density of 5e19m-3. If successful, the axisymmetric tandem mirror extension of the GDT idea could lead to a Q {approx} 10 power plant of modest size and would yield important applications at lower Q. In addition to the GDT method, there are four other ways to augment stability that have been demonstrated; including: plasma rotation (MCX), diverter coils (Tara), pondermotive (Phaedrus & Tara), and end wall funnel shape (Nizhni Novgorod). There are also 5 stabilization techniques predicted, but not yet demonstrated: expander kinetic pressure (KSTM-Post), Pulsed ECH Dynamic Stabilization (Post), wall stabilization (Berk), non-paraxial end mirrors (Ryutov), and cusp ends (Kesner). While these options should be examined further together with conceptual engineering designs. Physics issues that need further analysis include: electron confinement, MHD and trapped particle modes, analysis of micro stability, radial transport, evaluation and optimization of Q, and the plasma density needed to bridge to the expansion-region. While promising all should be examined through increased theory effort, university-scale experiments, and through increased international collaboration with the substantial facilities in Russia and Japan The conventional wisdom of magnetic mirrors was that they would never work as a fusion concept for a number of reasons. This conventional wisdom is most probably all wrong or not applicable, especially for applications such as low Q (DT Neutron Source) aimed at materials testing or for a Q {approx} 3-5 fusion neutron source applied to destroying actinides in fission waste and breeding of fissile fuel.
Simonen, T
Modeling and analysis of hydrogen detonation events in the Advanced Neutron Source reactor containment
This paper describes salient aspects of the modeling, analyses, and evaluations for hydrogen detonation in selected regions of the Advanced Neutron Source (ANS) containment during hypothetical severe accident conditions. Shock wave generation and transport modeling and analyses were conducted for two stratified configurations in the dome region of the high bay. Principal tools utilized for these purposes were the CTH and CET89 computer codes. Dynamic pressure loading functions were generated for key locations and used for evaluating structural response behavior for which a finite-element model was developed using the ANSYS code. For the range of conditions analyzed in the two critical dome regions, it was revealed that the ANS containment would be able to withstand detonation loads without failure.
Taleyarkhan, R.P.; Georgevich, V.; Kim, S.H.; Valenti, S.N.; Simpson, D.B. [Oak Ridge National Lab., TN (United States); Sawruk, W. [Gilbert/Commonwealth, Inc., Reading, PA (United States)
Basics of Fusion-Fissison Research Facility (FFRF) as a Fusion Neutron Source
FFRF, standing for the Fusion-Fission Research Facility represents an option for the next step project of ASIPP (Hefei, China) aiming to a first fusion-fission multifunctional device [1]. FFRF strongly relies on new, Lithium Wall Fusion plasma regimes, the development of which has already started in the US and China. With R/a=4/1m/m, Ipl=5 MA, Btor=4-6 T, PDT=50- 100 MW, Pfission=80-4000MW, 1 m thick blanket, FFRF has a unique fusion mission of a stationary fusion neutron source. Its pioneering mission of merging fusion and fission consists in accumulation of design, experimental, and operational data for future hybrid applications.
Leonid E. Zakharov
Fuel plate stability experiments and analysis for the Advanced Neutron Source
The planned reactor for the Advanced Neutron Source (ANS) will use closely spaced arrays of involute-shaped fuel plates that will be cooled by water flowing through the channels between the plates. There is concern that at certain coolant flow velocities, adjacent plates may deflect and touch, with resulting failure of the plates. Experiments have been conducted at the Oak Ridge National Laboratory to examine this potential phenomenon. Results of the experiments and comparison with analytical predictions are reported. The tests were conducted using full-scale epoxy plate models of the aluminum/uranium silicide ANS involute-shaped fuel plates. Use of epoxy plates and model theory allowed lower flow velocities and pressures to explore the potential failure mechanism. Plate deflections and channel pressures as functions of the flow velocity are examined. Comparisons with mathematical models are noted.
Swinson, W.F.; Battiste, R.L.; Luttrell, C.R.; Yahr, G.T.
A 4p BaF2 detector for (n,g) cross section measurements at a spallation neutron source
The quest for improved neutron capture cross sections for advanced reactor concepts, transmutation of radioactive wastes as well as for astrophysical scenarios of neutron capture nucleosynthesis has motivated new experimental efforts based on modern techniques. Recent measurements in the keV region have shown that a 4p BaF2 detector represents an accurate and versatile instrument for such studies. The present work deals with the potential of such a 4p BaF2 detector in combination with spallation neutron sources, which offer large neutron fluxes over a wide energy range. Detailed Monte Carlo simulations with the GEANT package have been performed to investigate the critical backgrounds at a spallation facility, to optimize the detector design, and to discuss alternative solutions.
M. Heil; R. Reifarth; M. M. Fowler; R. C. Haight; F. K�ppeler; R. S. Rundberg; E. H. Seabury; J. L. Ullmann; J. B. Wilhelmy; K. Wisshak
Experience using laser-wire beam profile measurement to perform transverse beam matching in the SNS superconducting linac is discussed. As the SNS beam power is ramped up to 1 MW, transverse beam matching becomes a concern to control beam loss and residual activation in the linac. In our experiments, however, beam loss is not very sensitive to the matching condition. In addition, we have encountered difficulties in performing a satisfactory transverse matching with the envelope model currently available in the XAL software framework. Offline data analysis from multi-particle tracking simulation shows that the accuracy of the current online model may not be sufficient for modeling the SC linac.
Zhang, Yan [ORNL; Cousineau, Sarah M [ORNL; Liu, Yun [ORNL
The New Munich Neutron Source FRM II: Overview and Uses for Biological Studies
Neutron Physics at NIST M. Arif 8th UCN Workshop St. Petersburg Moscow, Russia June 11-21, 2011 #12;NCNR Guide Hall 20 MW Reactor #12;Neutron Physics at the NCNR Beam Flux n cm-2 s-1 Peak Wavelength Facility Low Scatter Neutron Dosimeter Calibration Facility #12;December 31, 2012 Physics Physics Physics
Doster, Wolfgang
Neutronic Aspects and Recent Experimental Results with ...
... Neutronic Aspects and Recent Experimental Results with Methane Moderators at IUCF Low Energy Neutron Source (LENS). ...
NXS 2013 - Neutron Scattering School
5th National School on Neutron and X-Ray Scattering 5th National School on Neutron and X-Ray Scattering August 10-24, 2013 Argonne National Laboratory, Argonne, IL Oak Ridge National Laboratory, Oak Ridge, TN NXS2013 Schedule Participants Image Gallery Travel Info Thank you Lectures Lecture Notes/Videos Experiments ANL Facilities ANL Map (jpg) ANL Map (pdf) ANL Visitor's Guide ORNL Facilities HFIR Facility SNS Facility HFIR/SNS Map Wireless Networks ORNL Safety & Security Rules ORNL NSSA Weblink Contacts ANL ORNL 2013 NXS School Participants 2013 NXS Participants. NXS interveiws 2013 Click the image to download the video. Video Interviews: Participants answer questions about their experiences at NXS 2011. Your feedback about lectures and experiments is important for evaluating this year's Neutron and X-ray Scattering School and for making improvements for future participants. We sincerely hope that each of you will complete the survey by the end of the school.
Neutron range spectrometer
A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are colliminated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated neutron beam. The counter determines positions along the collimation axis of interactions between the neutrons in the neutron beam and a neutron-absorbing material in the counter. From the interaction positions, a computer analyzes the data and determines the neutron energy spectrum of the neutron beam. The counter is preferably shielded and a suitable neutron-absorbing material is He-3. 1 fig.
Manglos, S.H.
SHIPPING AND ALIGNMENT FOR THE SNS CRYOMODULE* T. Whitlatch
a similar (CEBAF ¼) cryomodule with accelerometers during a road test of approximately 300 miles. A modal understand the shipping environment, a road test using an existing CEBAF ¼ cryomodule was performed. The CEBAF ¼ cryomodule cavity is aligned and supported by similar attachment rods as used in the SNS design
Calculations for predicting the distribution of the products of spallation reactions between high energy protons and target materials are well developed and are used for design and operational applications in many projects both within DOE and in other arenas. These calculations are based on theory and limited experimental data that verifies rates of production of some spallation products exist. At the Spallation Neutron Source, a helium stream from the mercury target flows through a system to remove radioactivity from this mercury target offgas. The operation of this system offers a window through which the production of noble gases from mercury spallation by protons may be observed. This paper describes studies designed to measure the production rates of twelve noble gas isotopes within the Spallation Neutron Source mercury target.
DeVore, Joe R [ORNL; Lu, Wei [ORNL; Schwahn, Scott O [ORNL
Progress on the RF Coupling Coil Module Design for the MICE Channel
Spallation Neutron Source (SNS) type ceramic RF windows arecouplers together with the SNS-type ceramic RF window. Ahigh power tested now at the SNS RF test lab. Cavity length
The high current transport experiment for heavy ion inertial fusion
accelconf/l02/PAPERS/TU483.PDF �SNS parameters list�, ReportScience, November 2003, SNS-100000000- PL0001-R10, http://the Spallation Neutron Source (SNS) Front End [29,30,31] and
Frustrated spin correlations in diluted spin ice Ho2-xLaxTi2O7
Acknowledgments ORNL/SNS is managed by UT-Battelle, LLC, forat the Spallation Neutron Source (SNS) in Oak Ridge [23]. Intime of the experiments, SNS was running at 30 Hz, making a
Ehlers, G.
Preliminary Concept for the Project X CW Radio Frequency Quadrupole (RFQ)
Spallation Neutron Source (SNS) Front End [3] as well as awas used successfully on the SNS RFQ, which used Glidcop forsimilar to those used on the SNS RFQ. The preliminary design
Virostek, S. P.
Community petascale project for accelerator science and simulation: Advancing computational science for future accelerators and accelerator technologies
spallation neutron sources (SNS, LANSCE) and its synchrotronII, LHC, RHIC, NLC, ILC design, SNS, and LCLS [8]. They wereILC damping ring modeling, SNS, RIKEN cyclotron injector,
Spentzouris, Panagiotis
Parametic Study of the current limit within a single driver-scale transport beam line of an induction Linac for Heavy Ion Fusion
of the RIA or SNS beam lines. ..the Spallation Neutron Source (SNS) Front End [38,39,40] anddistributions. For example the SNS linac [38,166] or Rare
Prost, Lionel Robert
Newly designed field control module for the SNS
The low-level RF (LLRF) control system for the Spallation Neutron Source has undergone some recent hardware changes. The intended Field and Resonance Control Module (FRCM) design has been re-vamped to minimize functionality and ease implementation. This effort spans a variety of disciplines, and requires parallel development with distinct interface controls. This paper will discuss the platform chosen, the design requirements that will be met, and the parallel development efforts ongoing.
Regan, A. H. (Amy H.); Kasemir, K. U. (Kay-Uwe); Kwon, S. I. (Sung-Il); Power, J. F. (John F.); Prokop, M. S. (Mark S.); Shoaee, H. (Hamid); Stettler, M. W. (Matthew W.); Doolittle, L. (Lawrence); Ratti, A. (Alessandro); Champion, M. S. (Mark S.); Swanson, C.
Report of the Advanced Neutron Source (ANS) safety workshop, Knoxville, Tennessee, October 25--26, 1988
On October 25--26, 1988, about 60 people took part in an Advanced Neutron Source (ANS) Safety Workshop, organized in cooperation with the Oak Ridge Operations (ORO) Office of the Department of Energy (DOE) and held in Knoxville, Tennessee. After a plenary session at which ANS Project staff presented status reports on the ANS design, research and development (R and D), and safety analysis efforts, the workshop broke into three working groups, each covering a different topic: Environmental and Waste Management, Applicable Regulatory Safety Criteria and Goals, and Reactor Concepts. Each group was asked to review the Project's approach to safety-related issues and to provide guidance on future reactor safety needs or directions for the Project. With the help of able chairmen, assisted by reporters and secretarial support, the working groups were extremely successful. Draft reports from each group were prepared before the workshop closed, and the major findings of each group were presented for review and discussion by the entire workshop attendance. This report contains the final version of the group reports, incorporating the results of the overall review by all the workshop participants.
Buchanan, J.R.; Dumont, J.N.; Kendrick, C.M.; Row, T.H.; Thompson, P.B.; West, C.D.; Marchaterre, J.F.; Muhlheim, M.D.; McBee, M.R. (comp.)
Silicon Photo-Multiplier radiation hardness tests with a beam controlled neutron source
We report radiation hardness tests performed at the Frascati Neutron Generator on silicon Photo-Multipliers, semiconductor photon detectors built from a square matrix of avalanche photo-diodes on a silicon substrate. Several samples from different manufacturers have been irradiated integrating up to 7x10^10 1-MeV-equivalent neutrons per cm^2. Detector performances have been recorded during the neutron irradiation and a gradual deterioration of their properties was found to happen already after an integrated fluence of the order of 10^8 1-MeV-equivalent neutrons per cm^2.
Angelone, M; Faccini, R; Pinci, D; Baldini, W; Calabrese, R; Cibinetto, G; Ramusino, A Cotta; Malaguti, R; Pozzati, M
M. Angelone; M. Pillon; R. Faccini; D. Pinci; W. Baldini; R. Calabrese; G. Cibinetto; A. Cotta Ramusino; R. Malaguti; M. Pozzati
Replacing a 252Cf source with a neutron generator in a shuffler - a conceptual design performed with MCNPX
The {sup 252}Cf shuffler has been widely used in nuclear safeguards and radioactive waste management to assay fissile isotopes, such as {sup 235}U or {sup 239}Pu, present in a variety of samples, ranging from small cans of uranium waste to metal samples weighing several kilograms. Like other non-destructive assay instruments, the shuffler uses an interrogating neutron source to induce fissions in the sample. Although shufflers with {sup 252}Cf sources have been reliably used for several decades, replacing this isotopic source with a neutron generator presents some distinct advantages. Neutron generators can be run in a continuous or pulsed mode, and may be turned off, eliminating the need for shielding and a shuffling mechanism in the shuffler. There is also essentially no dose to personnel during installation, and no reliance on the availability of {sup 252}Cf. Despite these advantages, the more energetic neutrons emitted from the neutron generator (141 MeV for D-T generators) present some challenges for certain material types. For example when the enrichment of a uranium sample is unknown, the fission of {sup 238}U is generally undesirable. Since measuring uranium is one of the main uses of a shuffler, reducing the delayed neutron contribution from {sup 238}U is desirable. Hence, the shuffler hardware must be modified to accommodate a moderator configuration near the source to tailor the interrogating spectrum in a manner which promotes sub-threshold fissions (below 1 MeV) but avoids the over-moderation of the interrogating neutrons so as to avoid self-shielding. In this study, where there are many material and geometry combinations, the Monte Carlo N-Particle eXtended (MCNPX) transport code was used to model, design, and optimize the moderator configuration within the shuffler geometry. The code is then used to evaluate and compare the assay performances of both the modified shuffler and the current {sup 252}Cf shuffler designs for different test samples. The matrix effect and the non-uniformity of the interrogating flux are investigated and quantified in each case. The modified geometry proposed by this study can serve s a guide in retrofitting shufflers that are already in use.
Schear, Melissa A [Los Alamos National Laboratory; Tobin, Stephen J [Los Alamos National Laboratory
Implementation and qualification of neutronic calculation methodology in subcritical reactors driven by external neutron sources and applications.
??This works had as goal to investigate calculational methodologies on subcritical source driven reactor, such as Accelerator Driven Subcritical Reactor (ADSR) and Fusion Driven Subcritical� (more)
Thiago Carluccio
Dr. Andrey Podlesnyak | ORNL Neutron Sciences
Andrey Podlesnyak Andrey Podlesnyak Dr. Andrey Podlesnyak Instrument Scientist: Cold Neutron Chopper Spectrometer (CNCS), SNS Education PhD in Physics, Institute for Metal Physics, Ekaterinburg, Russia Description of Research 2008 - present Instrument Scientist, Cold Neutron Chopper Spectrometer, Neutron Scattering Sciences Division, Oak Ridge National Laboratory 2006 - 2008 Instrument Scientist, single crystal diffractometer E-4, Hahn-Meitner-Institut, Berlin, Germany 2002 - 2006 Instrument Scientist, TOF spectrometer FOCUS, Laboratory for Neutron Scattering, ETH Zurich & Paul Scherrer Institute, Switzerland 2000 - 2002 Instrument Scientist, triple-axis spectrometer TASP, Laboratory for Neutron Scattering, ETH Zurich & Paul Scherrer Institute, Switzerland 1994 - 2000 Physicist, Institute for Metal Physics, Ekaterinburg, Russia
Tagged Neutron Source for API Inspection Systems with Greatly Enhanced Spatial Resolution
We recently developed induced fission and transmission imaging methods with time- and directionally-tagged neutrons offer new capabilities for characterization of fissile material configurations and enhanced detection of special nuclear materials (SNM). An Advanced Associated Particle Imaging (API) generator with higher angular resolution and neutron yield than existing systems is needed to fully exploit these methods.
Directorate Organization | ORNL Neutron Sciences
ORNL Neutron Sciences Directorate The Neutron Sciences Directorate (NScD) manages and operates the Spallation Neutron Source and the High Flux Isotope Reactor, two of the world's...
DOE/EIS-0247; Draft Environmental Impact Statement Construction and Operation of the Spallation Neutron Source, December 1998
December 1998 December 1998 Construction and Operation of the S PALLATION N EUTRON S OURCE DRAFT ENVIRONMENTAL IMPACT STATEMENT U.S. Department of Energy Office of Science DOE/EIS-0247 Construction and Operation of the Spallation Neutron Source Facility Draft Environmental Impact Statement U.S. Department of Energy Office of Science December 1998 DOE/EIS-0247 Draft, December 1998 Cover Sheet COVER SHEET RESPONSIBLE AGENCY: U.S. Department of Energy (DOE) TITLE: Draft Environmental Impact Statement (DEIS), Construction and Operation of the Spallation Neutron Source (DOE/EIS-0247) LOCATIONS OF ALTERNATIVE SITES: Illinois, New Mexico, New York, and Tennessee. CONTACT: For further information on this document, write or call: Mr. David Wilfert, EIS Document Manager U.S. Department of Energy Oak Ridge Operations Office
Vol. 31 (2000) ACTA PHYSICA POLONICA B No 1 TRANSMUTATION OF ISOTOPES ECOLOGICAL AND ENERGY PRODUCTION
Spallation Neutron Source (SNS) [13] project and European Spallation Source (ESS)[14.] The great advantages Technology: Report to Congress, DOE October, 1999. 13. Spallation Neutron Source home page: http://www.ornl.gov/sns
Research Highlights | Neutron Science | ORNL
Research Highlights Research Highlights Biology & Medicine Biotechnology & Energy Fundamental Physics Imaging Magnetism Materials Nanotechnology Superconductivity Facilities and Capabilities Instruments User Program Publications and Resources Science and Education News and Awards NScD Careers Supporting Organizations Neutron Science Home | Science & Discovery | Neutron Science | Research Highlights SHARE Research Highlights No current Research Highlights found. 1-10 of 43 Results Comprehensive phonon "map" offers direction for engineering new thermoelectric devices January 08, 2014 - To understand how to design better thermoelectric materials, researchers are using neutron scattering at SNS and HFIR to study how a compound known as AgSbTe2, or silver antimony telluride, is
Jessica Travierso Austin Peay State University
The Spallation Neutron Source (SNS) is a state of the art accelerator-based neutron source at Oak Ridge National Laboratory (ORNL) that was officially completed in May of 2006. When at full power, the SNS will produce experimental backscattering data from the SNS. The Fitting GUI SNS Portal GUI will be added to simulation tab
Fuel Cycle Optimization of a Helium-Cooled, Sub-Critical, Fast Transmutation of Waste Reactor with a Fusion Neutron Source.
??Possible fuel cycle scenarios for a helium-cooled, sub-critical, fast reactor with a fusion neutron source for the transmutation of spent nuclear fuel have been analyzed.� (more)
Maddox, James Warren
SNS 110040000-PC0002-R00 Policy for Use of Instruments
HFIR SNS NumberofProposals Low-Q TAx Diffraction ToF Instrument General User Proposals Submitted NSc18 130 137 43 164 233 128 166 118 301 90 229 237 180 133 145 131 251 164 29 31 HFIR SNS Numberof 156170 242212 359 2008-A 2008-B 2009-A 2010-A 2010-B 2008-A 2008-B 2009-A 2010-A 2010-B HFIR SNS General
Superconducting Research for ITER Superconducting Research for ITER Materials Engineering Research at SNS Helps International Collaboration on Fusion Energy Research Contact: Xun-Li Wang May 2011, Written by Deborah Counce Scientists and engineers at ORNL are working with the ITER Organization and the Japanese Atomic Energy Agency to resolve issues with a critical component of ITER's experimental fusion reactor. ITER is the international research facility in southeastern France whose mission is to demonstrate the feasibility of fusion as a practical long-term energy source. VULCAN VULCAN, engineering diffractometer at SNS. The VULCAN Engineering Diffractometer at SNS is being used to examine superconducting cables for ITER's central solenoid magnet, which induces the electrical current needed to confine and shape the plasma inside the
COMMISSIONING OF THE SNS FRONT-END SYSTEMS AT BERKELEY LAB*Details of other MEBT commissioning efforts, especiallywere provided by LANL. Commissioning topics included beam
Resonant Andreev transmission in two-dimensional array of SNS junctions.
We present an experimental study of transport properties of a large two-dimensional array of superconductor-normal-metal-superconductor (SNS) junctions comprised of the nanopatterned superconducting film, ensuring that NS interfaces of our SNS junctions are highly transparent. We find the anomalously high charge transmission at certain applied voltages commensurate with the magnitude of the gap in superconducting islands. This indicates the nonlocal nature of the charge transfer in multiply connected SNS systems. We propose the mechanism of the correlated transmission of Cooper pairs in large arrays of SNS junctions based on the combined action of the proximity effect and the simultaneous Andreev conversion processes at many NS-interfaces.
Baturina, T. I.; Mironov, A. Yu.; Vinokur, V. M.; Chtchelkatchev, N. M.; Glatz, A.; Nasimov, D. A.; Latyshev, A. V.; Materials Science Division; Inst. Semiconductor Physics; Russian Academy of Science; Moscow Inst. of Physics and Technology
Motivations and Engagement: Environmental Communication on SNS in China and Sweden.
?? As the name suggests and according to the developers� intention, Social Networking Sites (SNS) are designed as tools for users to make friends and� (more)
Fang, Weiwei
Contact ORNL Neutron Sciences
Crone Administrative Assistant Wendy Brooks SNS Instrument Operations Bobby Lee Cross HFIR Instrument Operations Gary W. Lynn HFIR Instrument Engineering Doug Selby SNS...
of the National Research Council. Full article ... Distance Learning Students Visit SNS Powder Diffractometer Students at the POWGEN Powder Diffractometer at SNS Ashfia Huq,...
Liquid lithium target as a high intensity, high energy neutron source
This invention provides a target jet for charged particles. In one embodiment the charged particles are high energy deuterons that bombard the target jet to produce high intensity, high energy neutrons. To this end, deuterons in a vacuum container bombard an endlessly circulating, free-falling, sheet-shaped, copiously flowing, liquid lithium jet that gushes by gravity from a rectangular cross-section vent on the inside of the container means to form a moving web in contact with the inside wall of the vacuum container. The neutrons are produced via break-up of the beam in the target by stripping, spallation and compound nuclear reactions in which the projectiles (deuterons) interact with the target (Li) to produce excited nuclei, which then "boil off" or evaporate a neutron.
Parkin, Don M. (Los Alamos, NM); Dudey, Norman D. (Glen Ellyn, IL)
Measurements of the cold neutron spectrum from the super critical hydrogen cold source at the High Flux Isotope Reactor at Oak Ridge National Laboratory were made using time-of-flight spectroscopy. Data were collected at reactor power levels of 8.5MW, 42.5MW and 85MW. The moderator temperature was also varied. Data were collected at 17K and 25K while the reactor power was at 8.5MW, 17K and 25K while at 42.5MW and 18K and 22K while at 85MW. The purpose of these measurements was to characterize the brightness of the cold source and to better understand the relationship between reactor power, moderator temperature, and cold neutron production. The authors will discuss the details of the measurement, the changes observed in the neutron spectrum, and the process for determining the source brightness from the measured neutron intensity.
Robertson, Lee [ORNL; Iverson, Erik B [ORNL
Theory and Analysis of the Feynman-Alpha Method for Deterministically and Randomly Pulsed Neutron Sources
contract FIKW-CT-2000-00063. REFERENCES 1. R. UHRIG, Random Noise Techniques in Nuclear Reactor Systems. Conf. New Frontiers of Nuclear Technology: Reactor Phys- ics (PHYSOR 2002), Seoul, Korea, October 7 Determination in Accelerator Driven Nuclear Reactors by Statistics from Neutron Detectors ~Feynman-Alpha Method
Pázsit, Imre
The temperature dependence of ultra-cold neutron wall losses in material bottles coated with deuterated polystryene
Ultra-cold neutrons (UCN) from the LANSCE super-thermal deuterium source were used to fill an acrylic bottle coated with deuterated polystyrene. The bottle was constructed to minimize losses through the filling valve. The storage time was extracted from a series of measurements where the number of neutrons was counted after they were held in the bottle for durations varying from 60-1200 s. The data were collected at temperatures of 18, 40, 65, 105, and 295 K. The data has been analyzed in terms of the ratio of the imaginary to real part of the wall potential. The analysis considers the velocity dependence of the probability per bounce of wall loss. The implication of these measurements for the SNS electric dipole moment search will be presented.
Cooper, Martiin D [Los Alamos National Laboratory; Bagdasarova, Yelena [Los Alamos National Laboratory; Clayton, Steven M [Los Alamos National Laboratory; Currie, Scott A [Los Alamos National Laboratory; Griffith, William C [Los Alamos National Laboratory; Ito, Takeyasu [Los Alamos National Laboratory; Makela, Mark F [Los Alamos National Laboratory; Morris, Cheistopher [Los Alamos National Laboratory; Rahaman, Mohamad S [Los Alamos National Laboratory; Ramsey, John C [Los Alamos National Laboratory; Saunders, Alexander [Los Alamos National Laboratory; Rios, Raymond [IDAHO STATE UNIV.
Structural Materials Development for MFE and IFE
's Spallation Neutron Source/High Flux Isotope Reactor (SNS/HFIR), National Center for Computational Sciences
Methods for absorbing neutrons
A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.
Guillen, Donna P. (Idaho Falls, ID); Longhurst, Glen R. (Idaho Falls, ID); Porter, Douglas L. (Idaho Falls, ID); Parry, James R. (Idaho Falls, ID)
Superconductivity | ORNL Neutron Sciences
Research Highlights Research Highlights Superconductivity Neutron diffraction reveals semiconducting phase and contributes to new understanding of iron-based superconductors Contact: Huibo Cao New VULCAN tests of Japanese cable for US ITER's central magnet system (2012) Contact: Ke An ARCS maps collaborative magnetic spin behavior in iron telluride (2011) Published Work: "Unconventional Temperature Enhanced Magnetism in Fe1:1Te" Contact: Igor Zaliznyak Doug Scalapino discusses "common thread" linking unconventional superconducting materials (2011) Contact: Douglas Scalapino Materials Engineering Research at SNS Helps International Collaboration on Fusion Energy Scientists and engineers at ORNL are working with the ITER Organization and the Japanese Atomic Energy Agency to resolve issues with a critical
Tracking Stripped Proton Particles in SNS Ring Injection Momentum Dump Line
3D computer simulations are performed to study magnetic field distributions and particle trajectories along the SNS ring injection momentum dump line. Optical properties and transfer maps along the dump line are calculated. The stripped proton particle distributions on the dump window are analyzed. The study has provided useful information for the redesign of the SNS ring injection beam dump.
Wang, Jian-Guang [ORNL
Neutron reflecting supermirror structure
An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources.
Wood, James L. (Drayton Plains, MI)
An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. 2 figs.
Wood, J.L.
Superconductivity Superconductivity Research Highlights Superconductivity Archive New Neutron Studies Support Magnetism's Role in Superconductors Recent neutron scattering experiments give strong evidence that if superconductivity is related to a material's magnetic properties, the same mechanisms are behind both copper-based, high-temperature superconductors and the newly discovered iron-based superconductors. The research was performed at SNS and HFIR and the ISIS Facility at Rutherford Appleton Laboratory in England. (2010) Published Work: "Evolution of spin excitations into the superconducting state in FeTe1-xSex" Contact: Mark Lumsden Advances in Unconventional Iron-Based Superconductors The discovery of more diverse superconducting materials will lead to more
Characterization of a Be(p,xn) neutron source for fission yields measurements
We report on measurements performed at The Svedberg Laboratory (TSL) to characterize a proton-neutron converter for independent fission yield studies at the IGISOL-JYFLTRAP facility (Jyv\\"askyl\\"a, Finland). A 30 MeV proton beam impinged on a 5 mm water-cooled Beryllium target. Two independent experimental techniques have been used to measure the neutron spectrum: a Time of Flight (TOF) system used to estimate the high-energy contribution, and a Bonner Sphere Spectrometer able to provide precise results from thermal energies up to 20 MeV. An overlap between the energy regions covered by the two systems will permit a cross-check of the results from the different techniques. In this paper, the measurement and analysis techniques will be presented together with some preliminary results.
A. Mattera; P. Andersson; A. Hjalmarsson; M. Lantz; S. Pomp; V. Rakopoulos; A. Solders; J. Valldor-Bl�cher; D. Gorelov; H. Penttil�; S. Rinta-Antila; A. V. Prokofiev; E. Passoth; R. Bedogni; A. Gentile; D. Bortot; A. Esposito; M. V. Introini; A. Pola
Neutron source, linear-accelerator fuel enricher and regenerator and associated methods
A device for producing fissile material inside of fabricated nuclear elements so that they can be used to produce power in nuclear power reactors. Fuel elements, for example, of a LWR are placed in pressure tubes in a vessel surrounding a liquid lead-bismuth flowing columnar target. A linear-accelerator proton beam enters the side of the vessel and impinges on the dispersed liquid lead-bismuth columns and produces neutrons which radiate through the surrounding pressure tube assembly or blanket containing the nuclear fuel elements. These neutrons are absorbed by the natural fertile uranium-238 elements and are transformed to fissile plutonium-239. The fertile fuel is thus enriched in fissile material to a concentration whereby they can be used in power reactors. After use in the power reactors, dispensed depleted fuel elements can be reinserted into the pressure tubes surrounding the target and the nuclear fuel regenerated for further burning in the power reactor.
Steinberg, Meyer (Huntington Station, NY); Powell, James R. (Shoreham, NY); Takahashi, Hiroshi (Setauket, NY); Grand, Pierre (Blue Point, NY); Kouts, Herbert (Brookhaven, NY)
Novel Compact Accelerator-Based Neutron and Gamma Sources for Future Detector Calibration
Novel ultra-compact, electrically switchable, time-structured/pulsed, ~1-14 MeV-level neutron and photon generators have application embedded into large detector systems, especially calorimeters, for energy and operational calibration. The small sizes are applicable to permanent in-situ deployment, or able to be conveniently inserted into large high energy physics detector systems. For bench- testing of prototypes, or for detector module production testing, these compact n and gamma generators offer advantages.
Jennings, G; Winn, D R
Time-of-Flight Bragg Scattering from Aligned Stacks of Lipid Bilayers using the Liquids Reflectometer at the Spallation Neutron Source
Time-of-flight (TOF) neutron diffraction experiments on aligned stacks of lipid bilayers using the horizontal Liquids Reflectometer at the Spallation Neutron Source are reported. Specific details are given regarding the instrumental setup, data collection and reduction, phase determination of the structure factors, and reconstruction of the one-dimensional neutron scattering length density (NSLD) profile. The validity of using TOF measurements to determine the one-dimensional NSLD profile is demonstrated by reproducing the results of two well known lipid bilayer structures. The method is then applied to show how an antimicrobial peptide affects membranes with and without cholesterol.
Pan, Jianjun [ORNL; Heberle, Frederick A [ORNL; Carmichael, Justin R [ORNL; Ankner, John Francis [ORNL; Katsaras, John [ORNL
Educational Programs
Source (APS). The Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory are used to generate neutrons. These facilities are...
Palm top plasma focus device as a portable pulsed neutron source
Development of a palm top plasma focus device generating (5.2 {+-} 0.8) Multiplication-Sign 10{sup 4} neutrons/pulse into 4{pi} steradians with a pulse width of 15 {+-} 3 ns is reported for the first time. The weight of the system is less than 1.5 kg. The system comprises a compact capacitor bank, a triggered open air spark gap switch, and a sealed type miniature plasma focus tube. The setup is around 14 cm in diameter and 12.5 cm in length. The energy driver for the unit is a capacitor bank of four cylindrical commercially available electrolytic capacitors. Each capacitor is of 2 {mu}F capacity, 4.5 cm in diameter, and 9.8 cm in length. The cost of each capacitor is less than US$ 10. The internal diameter and the effective length of the plasma focus unit are 2.9 cm and 5 cm, respectively. A DC to DC converter power supply powered by two rechargeable batteries charges the capacitor bank to the desired voltage and also provides a trigger pulse of -15 kV to the spark gap. The maximum energy of operation of the device is 100 J (8 {mu}F, 5 kV, 59 kA) with deuterium gas filling pressure of 3 mbar. The neutrons have also been produced at energy as low as 36 J (3 kV) of operation. The neutron diagnostics are carried out with a bank of {sup 3}He detectors and with a plastic scintillator detector. The device is portable, reusable, and can be operated for multiple shots with a single gas filling.
Rout, R. K.; Niranjan, Ram; Srivastava, R.; Rawool, A. M.; Kaushik, T. C.; Gupta, Satish C. [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Mishra, P. [Materials Processing Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)
NEUTRON DETECTOR BENEFITS Portable, ... High Flux Isotope Reactor and Spallation Neutron Source. Several Homeland Security. LINKS TO ONLINE ...
Choppers - Instrument Support | ORNL Neutron Sciences
Neutron Choppers Neutron Choppers The primary mission of the Neutron Chopper Team is to provide functional, reliable, safe, and operationally proven neutron chopper systems as required by the SNS instrument beam lines. Type of Choppers Activities Facilities Equipment TOP2 T0 chopper installed and operating in a CTF lower level chopper test bay. (Click for a larger picture) Chopper technician Bill Jordan recording chopper balance data. Types of Choppers Neutron choppers are rotating mechanical devices designed to block the neutron beam for some fraction of each revolution of the chopper. Our goal is to have at least three different functional classes of neutron choppers available for user experiments. Most, if not all, of these will be designed in standard forms that are interchangeable among the instruments. Most
OSP WEEKLY FUNDING BULLETIN Volume 5, Issue 06 February 7, 2011
. 16 in a one-day symposium on Neutrons in Structural Biology and will tour the SNS and HFIR facilities) and Oak Ridge's Spallation Neutron Source (SNS) and High Flux Isotope Reactor (HFIR) facilities to provide
Alabama in Huntsville, University of
Conceptual Design for Replacement of the DTL and CCL with Superconducting RF Cavities in the Spallation Neutron Source Linac
The Spallation Neutron Source Linac utilizes normal conducting RF cavities in the low energy section from 2.5 MeV to 186 MeV. Six Drift Tube Linac (DTL) structures accelerate the beam to 87 MeV, and four Coupled Cavity Linac (CCL) structures provide further acceleration to 186 MeV. The remainder of the Linac is comprised of 81 superconducting cavities packaged in 23 cryomodules to provide final beam energy of approximately 1 GeV. The superconducting Linac has proven to be substantially more reliable than the normal conducting Linac despite the greater number of stations and the complexity associated with the cryogenic plant and distribution. A conceptual design has been initiated on a replacement of the DTL and CCL with superconducting RF cavities. The motivation, constraints, and conceptual design are presented.
Champion, Mark S [ORNL; Doleans, Marc [ORNL; Kim, Sang-Ho [ORNL
Uncontrolled beam loss is a major concern in the operation of a high intensity hadron linac. A low density cloud of particles with large oscillation amplitudes, so called halo, can form around the dense regular beam core. This halo can be a direct or indirect cause of beam loss. There is experimental evidence of halo growing in the SNS linac and limiting the further reduction of beam loss. A set of tools is being developed for detecting of the halo and investigating its origin and dynamics. The set includes high resolution emittance measurements in the injector, laser based emittance measurements at 1 GeV, and high resolution profile measurements along the linac. We will present our experience with useful measurement techniques and data analysis algorithms.
Aleksandrov, Alexander V [ORNL; Blokland, Willem [ORNL; Liu, Yun [ORNL; Long, Cary D [ORNL; Zhukov, Alexander P [ORNL
Accelerator based neutron source for neutron capture therapy B. Bayanov, Yu. Belchenko, V. Belov, V. Davydenko, A. Donin, A. Dranichnikov, A. Ivanov,
OF LOW-ENERGY NEUTRONS IN SOLAR FLARES AND THE IMPORTANCE OF THEIR DETECTION IN THE INNER HELIOSPHERE R 20375, USA; email@example.com 2 Department of Physics and Astronomy, Tel Aviv University, Tel ABSTRACT Neutron detectors on spacecraft in the inner heliosphere can observe the low-energy (
Awards 2007 | ORNL Neutron Sciences
7 7 Staff Awards: 2007 Chakoumakos elected MSA Fellow Bryan Chakoumakos Neutron scientist Bryan Chakoumakos was recently elected a fellow of the Mineralogical Society of America. A member of the Neutron Scattering Science Division, Bryan leads the Single-Crystal Diffraction Group. The group has five neutron scattering instruments in various stages of design and construction, located at HFIR and SNS. The MSA was founded in 1919 and, among other goals, encourages fundamental research on natural materials and supports education through its publications, educational grants, and courses. Pharos Neutron Detector System Researchers at the Department of Energy's Oak Ridge National Laboratory have won six R&D 100 Awards, given annually by R&D Magazine to the year's
Effects of an RTG power source on neutron spectroscopy measurements on the martian surface.
A continuing goal of Mars science is to identify the exact locations of near-surface water and/or hydrated minerals using in situ measurements. Recent data from the Mars Odyssey mission has used both neutron and gamma-ray spectroscopy to measure large amounts of water ice near both polar regions . Furthermore, these data have also determined that in the mid-latitude regions, there likely exist relatively large amounts of hydrogen (-4-7 equivalent H2O wt.%), although it is not certain in which form this hydrogen exists . While these are exciting results, one drawback of these measurements is that they are averaged over a large (-400 km) footp ri nt and do not reflect any small (<1 km) inhomogenieties in hydrogen abundance that likely exist on the Martian surface. For any future in situ mission (e g, Mars Smart Lander (MSL)) that seeks to measure and characterize nearsurface H 2O, especially in the mid-latitude regions, is will be necessary to know th e locati ons of the H20.
Lawrence, David J. (David Jeffery),; Elphic, R. C. (Richard C.); Wiens, R. C. (Roger C.)
The Role of Narcissism on Concerns for SNS Privacy: Vulnerable Narcissism in Threatening Situations.
??This study aims to identify psychological factors that predict one�s likelihood to disengage with privacy-threatening activities on Social Networking Sites (SNS). Particularly, it pays special� (more)
Kwolek, Elizabeth A.
Lead-Bismuth-Eutectic Spallation Neutron Source for Nuclear Transmuter Y. Gohar, J. Herceg, L Krajtl, D. Pointer, J. Saiveau, T. Sofu, and P. Finck
-driven test facility (ADTF). The ADTF is a major nuclear research facility that will provide multiple testing to operate as a user facility that allows testing advanced nuclear technologies and applications, materialLead-Bismuth-Eutectic Spallation Neutron Source for Nuclear Transmuter Y. Gohar, J. Herceg, L
Band-Structure, Optical Properties, and Defect Physics of the Photovoltaic Semiconductor SnS
SnS is a potential earth-abundant photovoltaic (PV) material. Employing both theory and experiment to assess the PV relevant properties of SnS, we clarify on whether SnS has an indirect or direct band gap and what is the minority carrier effective mass as a function of the film orientation. SnS has a 1.07 eV indirect band gap with an effective absorption onset located 0.4 eV higher. The effective mass of minority carrier ranges from 0.5 m{sub 0} perpendicular to the van der Waals layers to 0.2 m{sub 0} into the van der Waals layers. The positive characteristics of SnS feature a desirable p-type carrier concentration due to the easy formation of acceptor-like intrinsic Sn vacancy defects. Potentially detrimental deep levels due to SnS antisite or S vacancy defects can be suppressed by suitable adjustment of the growth condition towards S-rich.
Vidal, J.; Lany, S.; d'Avezac, M.; Zunger, A.; Zakutayev, A.; Francis, J.; Tate, J.
A diffusion theory model for optimization calculations of cold neutron sources
This summary describes a simple two-group diffusion model of an infinite slab, liquid deuterium (LD/sub 2/) cold source. The simplicity of the model permits us to obtain an analytical solution from which we can deduce the reason for the optimum thickness based solely on diffusion type phenomena. Also, a second more sophisticated model is described, and the results compared to a deterministic transport calculation. The good (particularly qualitative) agreement between the results suggests that diffusion theory methods can be used in parametric and optimization studies in order to avoid the generally more expensive transport calculations. 5 refs., 1 fig.
Azmy, Y.Y.